To provide a connector 6 provided so as to connect a coupler 5 for external wiring to a casing 2 of a control unit 1 and including an insertion port 63 of the coupler and a partition wall part 64 for partitioning the insertion port and a space in the casing, and further including a ventilation hole 66 formed on the partition wall part for communicating between the insertion port and the space in the casing, capable of preventing foreign material such as a water drop or the like intruding in the insertion port when detaching or attaching the coupler from intruding from the ventilation hole into the casing.

A protrusion part 67 protruding to a side of the insertion port 63 is protruded on a part for forming the ventilation hole 66 of the partition wall part 64, and the ventilation hole 66 is formed so as to pass thorough the protrusion part 67. The protrusion part 67 functions as a waterproof wall, and intrusion of the foreign material into the casing 2 through the ventilation hole 66 is prevented.