PURPOSE: To easily remove water drops and prevent electric shock by fixing a plate whose surface is formed with water repellent material to a casing and projecting a plug blade from a plate opening.

CONSTITUTION: A casing 1 is constructed with the first and second casings 2 and 3, and engaged with them by the first and second engaging projections 6 and 7. A plate 8 formed with fluorine resin having high water repellent capability is fixed to the front wall of the second casing 3. A set of plug blades 10 formed with conductive material are projected from a set of openings 9 formed in the plate 8. The plug blades 10 are insert-molded in a base 11 formed with synthetic resin, and connected to a primary terminal 12 of a step-down transformer through a conductive metal tool 13. Thereby electric shock is prevented in plug in.