Abstract: Economic regulation and antitrust policy are the main content of regulatory economics. In the economic policy, it is reflected in the relationship between industrial policy and competition policy, while in the financial sactor,it is the relationship between financial regulation and competition regulation. In the early postwar period, Japan formed a strict framework of antirust and regulation under the General Headquarters(GHQ). With the change in the U.S. policy towards Japan, there has been a situation for a long time in the financial sector where the competition authorities faded out and the regulatory authorities dominated. Since the 1970s, Japanese regulatory authorities have gradually relaxed the regulation of competition restrictions and promoted the competition in the financial sector.Especially under strong pressure from US in the period of Japan-US trade friction, a cooperative pattern of regulatory authorities and competition authority has to be formed with the same goal of financial stability. In spite of EU and US strengthening regulation and antitrust policy after the global financial crisis, Japanese government took no special measures in this period but established a new harmonious system between regulation and antitrust policy with the common goal of stimulating the vitality of financial institutions recently.

Key words: financial sector, competition regulation, financial regulation