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Chapter 2 Population and Households
This chapter covers population, vital statistics, migration and households. Statistical tables on population contain basic attributes such as the size of a population, the growth of population, regional distribution and demographic structure by age and sex, whereas the tables on vital statistics contain statistics concerning birth, death, stillbirth, marriage and divorce. The tables concerning the movement of population address the issue of daily movements by commuting and attending school as well as regional migration within Japan and entries into and departures from Japan. The tables on households cover basic attributes including the regional distribution of households, household members and family type.
Population by the "Population Census (Fundamental Statistics)"
The Statistics Bureau of the Ministry of Internal Affairs and Communications has been carrying out population censuses every five years since 1920. The population by the census is based on the "de facto" definition up to the special census in 1947, whereas the "de jure" definition has been used since 1950. "De facto population" means that a person is counted at the place where he/she is present as of the day of the census, whereas "de jure population" means that a person is counted at the place where he/she usually resides around the day of the census.
The population censuses from 1920 to 1940 included foreign residents working for foreign embassies, consulates and warships as well as residents with foreign nationalities. The special census in 1947 and the census in 1950 included foreign residents who usually lived in Japan except for those who were categorized under item 1 of each part in Article 2 in the "Aliens Registration Ordinance." Each census conducted since 1955 excludes  soldiers and civilian employees in foreign forces stationed in Japan and their families and  foreign diplomatic and consular corps (including their suits and families) stationed in Japan.
Each census carried out during the period from 1920 to 1940 included Korea, Taiwan and Karafuto as well as Hokkaido, Honshu, Shikoku, Kyushu and Okinawa. (Note: Korea was not included in the 1920 census.) Hence, in this report the populations of Korea, Taiwan and Karafuto were subtracted to compute the population of Japan for this period. The total population of the 1940 census includes soldiers and civilian employees in the Japanese forces stationed overseas. Regions that were not under the jurisdiction of the Japanese Administration were excluded from the special population census of 1947 and the population census of 1950.
From 1950 and onward, the population census includes Oshima-gun and Naze City in Kagoshima Prefecture, and from 1970 it includes the Ogasawara Islands. From 1975, Okinawa was included in the population census. As a result, only the so-called Northern Territories (consisting of the Habomai Islands, Shikotan Island, Kunashiri Island and Etorofu Island of Hokkaido) and Takeshima Island of Shimane Prefecture are excluded from the census after 1985 and onward.
Population of Densely Inhabited Districts
Densely Inhabited Districts were newly set up in the population census of 1960. This was because the conventional classification based on "cities" and "towns and villages" would not necessarily illuminate the characteristics of urban districts and rural districts due to the expansion of city areas through the merger of towns and to form new city.
The population of Densely Inhabited Districts means people who live in Densely Inhabited Districts, which is, in other words, urban districts.
In the population census, the population is surveyed as of zero o'clock midnight of the day of a census. As a result, it is called the "nighttime population." Data on the population of a place of work and a place of schooling were collected in the census of 1930 and every census from 1960 onward. The "population by place of work and place of schooling" is computed using the collected data. This population and the population of those who did not work or go to school constitute the "daytime population."
Temporary movements of people such as shopping and sightseeing are not considered in the daytime population. In the censuses of 1960 and 1965, persons attending school were limited to age 15 and over. Since 1970, pupils of age 14 or lower have been also asked for the place of school.
Birth, death, stillbirth, marriage and divorce
Birth, death, marriage, divorce, inflow and outflow (movement of population) are factors causing for fluctuations in the population. The former four factors are called "natural movements," whereas the latter two factors are called "social movements." The vital statistics ordinarily refers to statistics concerning natural movements of population.
Birth, death and stillbirth in vital statistics are recorded only when the place of its occurrence and the domicile address of the newborn, deceased or mother of the stillborn are registered in Hokkaido, Honshu, Shikoku, Kyushu or Okinawa (that is, Japanese persons).
The coverage of marriages in the vital statistics underwent several changes. Prior to 1943 it was limited to the case in which the address of a husband at the time of registration, or the address of a wife, in case a man is legally adopted into his wife's family, is in Hokkaido, Honshu, Shikoku, Kyushu or Okinawa and both husband and wife or either husband or wife has a domicile address in these areas (including Karafuto) (in other words, Japanese nationals). During the period from 1947 to 1949, it was limited to the case in which the place of marriage was within the above areas (excluding Karafuto). In 1950 and 1951 the address of a husband immediately before his marriage had to be within the above areas. Since 1952, the address of a husband at the time of registration needs to be within the above areas. In any case the domicile address of both husband and wife or either husband or wife should be within the above areas (Japanese nationals).
Similarly, the coverage of divorces in the vital statistics changed in the past. Prior to 1943, the address of a husband at the time of notification or the address of a plaintiff in a judicial divorce had to be within Hokkaido, Honshu, Shikoku, Kyushu or Okinawa and the domicile address, in the above areas (including Karafuto) (that is, Japanese nationals). In the period from 1947 to 1951, the address of a husband at the time of divorce had to be within the above areas (excluding Karafuto). Since 1952, the address of a husband at the time of registration must be within the above areas. In any cases, it was limited to the case in which both husband and wife or either husband or wife has his/her domicile address in the above areas (Japanese nationals).
The life table shows various functions that express the condition of mortality during a certain period of time. The functions include mortality rate, number of survivors, number of deaths, stationary population and life expectancy. These functions are computed on the basis of the number of deaths by each age and an average population or a central population by each age during a certain period of time.
Internal migration and movement by commuting or attending school
The regional movement of population can be roughly divided into movement that causes a change of address within a national boundary and movement across national borders. The former is called the internal migration, whereas the latter is called the "international migration." Statistics concerning the internal migration are compiled on the basis of the population census and the population movement report of the residents' register. In the population censuses of 1920, 1930, 1940 and 1950, the "place of birth" was surveyed, whereby it became possible to statically grasp cumulative results of demographic migration over a comparatively long period of time between the place of birth and the place of usual residence or the place of present residence. In the census of 1960 the "place of usual residence one year before" was surveyed, thereby enabling us to obtain detailed data on movements for the past one year. In the censuses of 1970 and 1980, "the time of movement to the place of present residence" and the "former address" were surveyed. Based on these data, statistics were compiled concerning population movements corresponding to the period of the past year and the period of the past five years. However, in the 1990 and 2000 censuses, the survey item included was only the "place of usual residence five years before," and the produced statistics are limited statistics to the movement of population in the past five years.
The "movement by commuting or attending school" is compiled, as well as the "daytime population," in the 1930 census and each census from 1955 and on. (The place of schooling was not included in the 1930 census.)
On the other hand, the Statistics Bureau of the Ministry of Internal Affairs and Communications compiles the "Population Movement Report of the Residents Register." This report is compiled from the data on the reports submitted by city, town and village offices via prefectural governments to the Ministry every quarter regarding people who have filed their moving-in notifications, based on the regulations of the Residents Basic Register Law.
Population of foreign residents and international movement migration
Data on the number of foreign residents by nationality are collected through the population censuses every 5 years. In addition, related data are available in the "Statistics on Registered Aliens" which have been compiled by the Ministry of Justice since 1948 when the "Aliens Registration Law" came into effect. With respect to the migration between Japan and other countries, a survey on Japanese living abroad was conducted before World War II. After the war, all entries into and departures from Japan are counted in the "immigration control statistics" in compliance with the Immigration Control Law enacted in 1951.
The Ministry of Foreign Affairs conducts the "Survey of the Number of Japanese Staying Outside Japan" to shed light on the population of Japanese nationals who resides outside the Japanese territories and excluded from the population census held every five years. The target of this survey includes people who possess Japanese nationality and who live or intend to live outside Japan for the period of three months or more around the date of the census.
On the other hand, each Japanese diplomatic establishment carries out a survey every year on the number of Japanese persons who stay within its jurisdiction. The results of the surveys are compiled as the "Survey of the Number of Japanese Staying Abroad."