A transformer (2A) outputs differential signals of a positive phase signal (Vout2Ap) having phase θ1+90° and a negative phase signal (Vout2An) having phase θ1−90°. A transformer (2B) outputs differential signals of a positive phase signal (Vout2Bp) having phase θ2+90° and a negative phase signal (Vout2Bn) having phase θ2−90°. An adding circuit (3) composes a pair of differential output signals, as signals corrected in phase error (θ1−θ2) generated in the transformers (2A, 2B), in a manner of summing up vectors of two pairs of the differential signals outputted from the transformers (2A, 2B) for the positive phase signal and the negative phase signal, respectively.