An adaptor includes a substrate, a first housing, and a flat cable. The substrate comprises a terminal hole. The first housing includes a first insertion hole and a second insertion hole. The substrate is inserted into the first insertion hole. The flat cable includes a plurality of conductors. Each of the conductors includes a conductor terminal. The flat cable passes through the second insertion hole. The conductor terminal is connected to the terminal hole. A direction in which the substrate is inserted into the first insertion hole is perpendicular to a direction in which the flat cable passes through the second insertion hole.