A light transmission module includes an optical converter for converting an electrical signal to an optical signal; a light transmission path for transmitting the optical signal converted by the optical converter; an electrical transmission path for transmitting an input electrical signal; and a control instructing unit for instructing stop of drive to the optical converter based on a detection of an input electrical signal. When an input electrical signal having a predetermined frequency is detected, the input electrical signal having the predetermined frequency is converted to an optical signal and transmitted in the light transmission path. When input of an electrical signal other than the predetermined frequency is detected, the electrical signal other than the predetermined frequency is transmitted by the electrical transmission path without being converted to an optical signal due to the stop of the drive of the optical converter.