A circuit module includes a wiring board on which are provided a ground plane, a signal line, and a conductive pattern for connection to an outer conductor of a coaxial cable including an inner conductor and the outer conductor. A common-mode choke coil is mounted on the wiring board such that one of coils of the common-mode choke coil connects the ground plane and the conductive pattern and that the other coil is inserted in the signal line. A communication element is mounted on the wiring board and includes a first signal terminal and a second signal terminal. The first signal terminal is connected to the common-mode choke coil via the signal line, and the second signal terminal is connected to the ground plane. A first capacitor is inserted in series in the signal line between the common-mode choke coil and the first signal terminal.