A waterproof structure is provided to fix a divided case with a smaller number of screws easily and prevent a waterproof member from being going crisscross due to vibration. A second case(2) overlaps with a first case(1) so as to be united. A waterproof member(4) is formed to be made of a material that can be elastically deformed to prevent infiltration of moisture from between the first and second cases. The second case includes a concave portion(23) having a sunken portion(231) to which a protrusion can be inserted. The waterproof member includes a convex sealing portion for preventing infiltration of moisture by being inserted to the concave portion. The convex sealing portion includes a protrusion(441) that can be inserted into the sunk portion so as to be engaged therein.
