Provided is an optical module used in a communication system employing a radio over fiber (ROF) technology delivering a radio frequency (RF) signal through an optical fiber. The optical module includes: an optical device; a signal line for transporting a radio frequency (RF) signal input from an external circuit to the optical device; and a resistor separately disposed from the signal line and having one end connected with the optical device, wherein the input impedance seen from the signal line is matched by the resistor. A bias voltage supplied to operate the optical device is applied through an inductor connected to the signal line between the optical device and a filter. Here, the filter formed by a pattern of the signal line prevents the bias voltage from being supplied to the external circuit. In order to amplify the RF signal input from the external circuit, an amplifier may be connected between the external circuit and the filter.