Abstract
This paper discusses the mechanism of chained negligence on the part of construction and related companies. The Japanese Construction Standard Law designates the minimum standard of building quality including anti-earthquake structure. However, the quality of condominium is hard to judge even after the use of building. Therefore, penalties on the low quality do not work in advance to ensure the quality, because monitoring institution does not have incentive to work hard. Incentive contract should be considered in ensuring the quality of buildings.