There are many great regional integrations in the world which initiated by developed countries. Those integration not only focus on politics but also developed as the economic integration. Some of these are seen as the great and developed regional integration because they can show their development socially, politically, and economically. Previously, ASEAN as regional integration in Southeast Asia rarely stated as great integration. But, nowadays ASEAN is stand as one best partner for economic cooperation. Many countries try to create good economic relations with ASEAN. Japan, South Korea and China are three industrialized countries that show their interest to establish economic cooperation with ASEAN. These countries have good economic relations with ASEAN. The number of trade between these countries and ASEAN increase significantly. In order to build good economic relations, these countries always establish this relations by supporting ASEAN in many ways. This research try to address the reason ASEAN become potential partner for economic cooperation for Japan, South Korea and China. This research is a qualitative research. This research use economic cooperation concept to identify the interest of these countries to ASEAN member countries as one of their best economic partners. This study finds that ASEAN is potential market for products from Japan, South Korea and China. It supports industries of these countries that is known as industrialized countries.