A printed circuit board (e.g., 103) includes capacitor elements (e.g., 121 and 122). The capacitor element (e.g., 121) returns a common mode current included in a signal output from a signal output terminal (e.g., 111) of a semiconductor element (e.g., 102), to a ground terminal (e.g., 113) of the semiconductor element (e.g., 102). The capacitor element (e.g., 122) returns a common mode current included in a signal output from a signal output terminal (e.g., 112) of the semiconductor element (e.g., 102), to the ground terminal (e.g., 113) of the semiconductor element (e.g., 102). The capacitor elements (e.g., 121 and 122) are arranged such that the mutual inductance between a parasitic inductance of the capacitor element (e.g., 121) and a parasitic inductance of the capacitor element (e.g., 122) for the common mode currents is a negative value. Accordingly, the effective inductances of the first and second capacitor elements for the common mode currents are reduced, which suppresses radiation noise.