The optical module includes a housing having a first opening for inputting or outputting a first electric signal, a second opening for inputting or outputting a second electric signal, and an optical signal port, one or more substrates disposed in the housing, to/from which the first electric signal is input/output and to/from which the second electric signal is input/output, an optical subassembly disposed in the housing and optically connected to the optical signal port, and a control circuit disposed in the housing and mounted on the substrate for controlling the optical subassembly, wherein the first electric signal is an electric signal input to or output from the optical subassembly, the second electric signal is an electric signal input to or output from the control circuit, and the second opening is provided on one side different from other side of the housing on which the first opening is provided.