A connector which serves as an optical transmitter in accordance with an embodiment of the present invention includes: a transmitting circuit configured to convert a data signal into an electric current signal, the data signal being a three-valued; and an LD configured to convert the electric current signal into an optical signal. The transmitting circuit detects, as an IDLE interval, an interval during which the data signal falls within a predetermined range that is between a high level and a low level. The transmitting circuit controls, during the IDLE interval, the electric current signal to be not greater than a threshold electric current of the LD.