Provided is an optical module in which a temperature of a semiconductor element to be subjected to temperature control is controlled to fall within a desired operating temperature range regardless of whether an environmental temperature is outside or inside the operating temperature range of the semiconductor element, and which is stably operated with low power consumption. A control section 30 determines, based on the environmental temperature having a temperature range of from a first temperature to a second temperature, a target temperature from a predetermined operating temperature range of from a third temperature to a fourth temperature. The control unit 30, an ATC circuit 34, a TEC control IC 12, and a TEC 24 control the temperature of a laser module 20 to become the target temperature. The first temperature is lower than the third temperature, and the second temperature is higher than the fourth temperature.