The legal weekly working hours in France have been reduced to 35 hours from 2000 by the so called "Aubry’s law" of 1998. After the victory of conservatives in the legislative election in 2002, the conservative government is trying to moderate the regulation of overtime work, stipulated by the Aubry's laws of 1998 and of 2002, in order to make it a dead letter. However, the 35 hours work is not only supported by the public, but also positively accepted by big companies. In this paper, I show the real feature of 35 hours work at the company level, based on my interviews with French carmakers, Renault, Peugeot SA, and Toyota Motor Manufacturing France (TMMF), and on their unions−management agreement about the application of 35 hours law of 1998. The main results of this analysis are as follows. Firstly, the negotiations between unions and management for fixing their agreement were the occasion to revise their industrial relations, because the problem of working hours was the central issue influencing entire life of employees, and have served to stabilize their relations. Secondly, the carmakers positively evaluate the 35 hours law, because the law has allowed the flexibility of work organization, by which they can realize considerable economy of scale. Thirdly, they are receiving the government’s financial aide given to the companies, which have applied 35 hours régime and increased their employment. For these last two reasons, the carmakers are able to lower their unit labor cost in spite of the increase in the hourly wage. At the last analysis, they surely profit from the 35 hours law, and have no reason to object to it.