A first fluid channel of a first body has a first inner diameter part and a second inner diameter part in an order that an inner diameter becomes smaller from a side where a nozzle is inserted. A second body has a second fluid channel capable of communicating with the first fluid channel and further has a first outer diameter part and a second outer diameter part which are inserted in the second inner diameter part in an order that an outer diameter becomes larger from the first fluid channel side. When the tip part of the second body is inserted in the first fluid channel, a wall surface provided at an end of the second inner diameter part along an axial direction, an end surface of the tip part of the second body and an inner circumferential surface of the second inner diameter part form a sealing groove.