The House of Councilors on Wednesday approved the government's ratification of a UNESCO treaty banning international trafficking in stolen cultural property and works of art.
The treaty makes it a criminal offense to export assets deemed to be cultural property or works of art without a government license, as well as import them.
The treaty also requires signatory countries to help recover and repatriate stolen cultural property.
Government officials said Japan will formalize the ratification procedure after passing related domestic laws.
The U.N. General Assembly adopted a resolution in 2001 urging member countries to speed up domestic legislative procedures to ratify the U.N. Educational, Scientific and Cultural Organization treaty.
Ratification of the treaty by Japan and other rich countries is vital for its implementation because stolen cultural assets often turn up in these countries for sale.