A technique is disclosed for an optical transceiver, where the frame ground is electrically isolated from the signal ground in a low frequency region and is conducted in a high frequency region, without applying a capacitor as a substantial circuit component. The transceiver includes a TOSA whose housing is grounded with the FG and connected with the driver with a FPC board. On the FPC board is formed with a parallel plate capacitor, one conductive pattern on the one surface is connected with the housing of the TOSA, while the other pattern in the opposite surface is connected with the SG. This parallel plate capacitor isolates the FG from the SG in low frequencies, while conducts the FG with the SG in high frequencies.