A first phase shift circuit (2) converts impedance to achieve impedance matching between a third terminal (1c) of a 90-degree hybrid circuit (1) and a first terminal (4a) of a first nonlinear element (4), and shifts a phase of a radio wave by 180 degrees, and a second phase shift circuit (3) converts impedance to achieve impedance matching between a fourth terminal (1d) of the 90-degree hybrid circuit (1) and a first terminal (5a) of a second nonlinear element (5), and shifts a phase of a radio wave by 90 degrees. As a result of this configuration, a conversion loss of radio waves can be reduced.