IDB has two Asian member countries, Japan and the Republic of Korea.

Japan's entry as a member of the IDB in 1976 formalized its growing economic relationship with Latin America and the Caribbean as well as the continuation of social and cultural ties that date back to the start of Japanese emigration to the region in the late 19th century. Latin America now has the largest group of ethnic Japanese outside Japan itself, numbering over a million people.

The Republic of Korea became the newest member of the IDB in March, 2005, signaling the growing ties between the Latin American and Caribbean countries with Asia. Its entry into the IDB brought not only additional resources to the institution, but also new ideas on how to approach development issues, based on the Asian experience of investments in education and technology, promotion of small business, and emphasis on the expansion of trade.

Japanese and Korean government representatives sit on the 47-member Board of Governors, the IDB's highest authority, which meets annually to make major policy decisions and review operations.

Japan represents on the 14-member Board of Executive Directors that, together with the Bank President, is responsible for IDB operations and administration.

Other than the Ordinary Capital, IDB is assigned to manage some of trust fund from member countries to use for wide range of financial and technical assistance. Japan Trust Fund   and Korean Trust Fund are the major technical cooperation fund at the Bank, which are applied for economy and social development. IDB manages Japan-IDB Scholarship Program and Japan Program to tighten relationship between Asia and Latin America/Caribbean.