Have you heard of a word “Koseki” (Family Registration, Family
Register)? They use it like “Koseki wo utsusu” or “Koseki ni hairu”.
Koseki is for Japanese only. Foreign residents
may not be familiar to it because there is another
foreigners, Alien Registration.
But Koseki will be significant matter if a
foreign resident marries a Japanese or has babies
What is Koseki?
It is the peculiar institution which there are
only a few countries adopt in the world including Japan.
It proves publicly relationship of persons who
live together in the unit of families. It has information like who
married who, number of children and names/birthdays of the children.
A single adult is able to make a new Koseki[It is
called “Bunseki” (Segregation from Family Register)], Marriage also
brings a new one.
Originally it started in old days as registration
of residents in the unit of houses for collection of government tax.
The name of Koseki (Ko: house, Seki: class,
qualification) comes from this origin.
Rulers had used it for grasping and controlling
people before, but Registration Law was changed and there is very
little concern about reverting back.
Koseki is still very significant institution for
We often need copy of Koseki as a certification
e.c. when getting employed, getting married, taking a driver’s
license or getting a passport.
Without Koseki would be in serious trouble.
Even though Koseki is so important and taken for
granted for Japanese, foreigners who come from the countries with
different institutions tend to hardly understand it including its
What is the difference?
For example, about marriage. In many European
countries, a marriage is legally acknowledged when a couple pledge
themselves in front of a person of authority.
The person is different by
the places: a mayor, a priest or a minister. He or she signs a
Meanwhile, a legal marriage in Japan is “to Join
someone’s Koseki”(to Resister at government office).
A marriage can not be legally acknowledged even
if you pledge in from of a person of authority and he or she signs a
However, a foreigner can not have a Koseki if he
or she marries a Japanese and registers.
Koseki is for Japanese only. A Japanese who
marries a foreigner will have a new Koseki which has the record that
he or she married - - - (partner’s name).
Meanwhile, for making Koseki of children of the
couple, registrations of marriage and birth are very important.
But their family structure and their
circumstances alter cases, please contact Koseki Jumin-ka
Koseki-gakari (Family Registration & Residents Section) TEL
047-436-2263 for detail information.