PROBLEM TO BE SOLVED: To prevent a plug cap, removed from the open end part of a case body in use of a hot water plug to become a non-use state, from interfering with connection work or release work of a plug part.SOLUTION: A hot water plug comprises: a case body 23 mounted to the tips of a pair of in-room side hot water pipelines 30a, 30b extending from a heat radiator 52 in a room; a pair of plug parts 25a, 25b surrounded by the case body 23 as a whole, and connecting flow channels; and a plug cap 20 capable of being detachably mounted to the open end part of the case body 23 in which a connection end part 27 for the plug parts 25a, 25b is exposed. In the hot water plug, a plug cap storage part 200 capable of storing the plug cap 20 in a fitting state is provided at a predetermined position of the case body 23.
