In the 70 years since the war, Japan has been a stable democratic country. It can be said that its success has been based on postwar economic reform. The problem is the relationship between such economic reform and guarantee of property rights. The Supreme Court of Japan has held that such economic reforms are constitutional even under the new Constitution. There are criticisms that such judgments of the Supreme Court disdain the guarantee of property rights under Japanese Constitution. However, from the idea that the guarantee of the Constitution will not expand beyond assets that conflict with realization of democracy and accumulation of excessive wealth was not necessarily all the consequences of individual ability, it should be considered that such a Supreme Court decision was valid. Therefore, under the Constitution, if the concentration of wealth becomes excessive again, according to democratic decisions, the government can adopt measures to resolve the concentration of wealth.