An optical module includes an optical modulator that performs optical modulation of transmission data, an optical modulator controller that controls the optical modulator, a memory that stores corresponding relationships between temperatures and set data with which modulation of the optical modulator is to be performed at an operating point voltage, a temperature sensor that measures a temperature in the optical module; and a setting circuit that refers the memory and searches for set data corresponding to measured temperature, and set the set data to the optical modulator controller.