To provide an automatic equalizer that selects an optimum sample timing by taking into account the effects of a demodulation component, a pre- cursor component and a post-cursor component and the like.

An automatic equalizer consists of a sampler 101, a substructure 102, an impulse response arithmetic circuit 103, a discrimination device 109, a sampling clock output circuit 111, and a reception signal estimate circuit 112. The sampling clock output circuit 111 determines as optimum sample timing where characteristic deterioration due to a pre-cursor component is small and characteristic enhancement by a post-cursor is high by taking into account a demodulation component, the pre-cursor component and the post-cursor component or the like. Thus, the sample timing is selected more optimally by taking the effect other than a peak value of impulse response into account.