To suppress peeling-off or cracks of a solder-fixing portion, which are caused by vibration during transportation or operation, in an optical modulator with FPC, thereby suppressing deterioration of radio-frequency characteristics of a signal path in an effective manner at low cost.An optical modulator 100 includes a flexible printed circuit (106) that performs electrical connection with a circuit substrate. The flexible printed circuit has a substantially quadrilateral shape. In the flexible printed circuit, a pad (210 and the like), which is electrically connected to the circuit substrate, is provided along one side of the substantial quadrilateral. In addition, in the flexible printed circuit, signal patterns (220 and the like), which are connected to signal lead pins (120 and the like) for signal transmission which is provided in the optical modulator, are provided in another side opposite to the one side. In addition, the flexible printed circuit includes an additional fixing portion (240 and the like) and/or a notched portion (810 and the like) which are configured to increase a natural vibration frequency of the flexible printed circuit in a state of being connected to the signal lead pin and the circuit substrate.