Conventional optical-transmission-type residual stress measuring apparatus cannot be used for completing the measurement of residual stress in an optical film having light reflective property, and conventional optical-reflection-type residual stress measuring apparatus is known failing to achieving the measurement of residual stress in an optical thin film having transparent or translucent property. In view of that, the present invention discloses a system for measuring residual stress in optical thin films, which is able to be utilized for achieving the residual stress measurement of respective optical thin film having transparent or translucent property and that of respective optical thin film having light reflective property. Therefore, it is helpful for largely reducing both the purchase cost and the maintenance cost by only purchasing the residual stress measuring system provided by the present invention instead of simultaneously purchasing the aforesaid two different types of residual stress measuring apparatuses.