The dereverberation problem can be solved by attacking magnitudes of time frequency transformation coefficients. In a spectrum frequency band, in harmonics, coefficients have a predictable pattern in phase. In this paper we propose a formulation for dereverberation problem which employs phase information in addition to magnitude information. In order to solve this problem we make use of a minimization problem. We solve the minimization problem with an iterative method. We discuss the performance of proposed method with experiments.