The optical phase distribution measurement is an important technology for many industrial applications. However, it requires a high precision measurement instrument which usually is expensive, delicate and requires laborious maintenance care. In this study, a new method which reconstructs optical phase distribution from intensity images has been developed. This method enables simple phase distribution measurement without expensive optical equipments and installation space. Firstly, the light is differently modulated by some optical systems, and intensity images of modulated light are measured by CCD camera. An inverse problem which reconstructs the phase distribution from the proposed measurement system is set up. This inverse problem is reduced to an unconstrained optimization problem which can be solved with non-linear optimization method such as BFGS method. The ill-posedness of the problem was overcome with regularization using a priori information whose unknown phase distribution is smooth. The effectiveness of the proposed method was demonstrated through some numerical simulation.