A resin molded body includes a connector unit having a side wall and an inner wall, both of which define a fitting chamber to which a mating connector is fitted and having a terminal penetrating through the inner wall and extending in a fitting direction, a substrate accommodating unit accommodating a circuit substrate to which the terminal is connected, and a device accommodating unit accommodating a device connected to the circuit substrate. The resin molded body is an integral molded product made of resin. A connecting portion has a plate shape extending outwards from the inner wall of the connector unit, and a second thickness thinner than a first thickness of the inner wall. The connecting portion is linked to the device accommodating unit.