The cabinet approved the bill that would mean Japan signing the 1980 Hague Convention. It would extend custody rights to non-Japanese parents whose children are moved to Japan by their former spouse.
The bill is now set to be debated in parliament.
Japan is the only major industrial nation that has not signed the treaty and has been pressured in recent years by the United States and other countries to do so.
Japanese courts almost never grant custody to foreign parents, particularly fathers, when international marriages break up.