Optical modulator with FPC and optical transmission device using same

A microwave band optical modulator which performs an optical modulation by a microwave band electrical signal, comprising:

• a flexible wiring board that makes an electrical connection with a circuit board,
• wherein the flexible wiring board has a substantially quadrilateral shape,
• pads to be electrically connected to the circuit board are formed on the flexible wiring board along one side of the substantially quadrilateral shape, and
• in order to release mechanical stress applied to a side or an end portion of the flexible wiring board and/or prevent propagation of a strain generated in the side or the end portion, the flexible wiring board has a cutout or notch disposed on a side adjacent to the one side, and the cutout or notch is provided from a portion of at least one side of the substantially quadrilateral shape toward an inside of the flexible wiring board, and
• the pads are foamed from the one side to a position of a distance a, and
• the cutout or notch is formed at a position within a distance 1.25×a from the one side.