A blood circuit connector includes: a main body having a cylindrical shape and provided with a first opening end and a second opening end a plug having a bottomed cylindrical shape and detachably attached to the first opening end and a connection part configured to connect the main body and the plug. The plug includes a side wall loosely fitted to an outer circumferential surface of the first opening end. The connection part includes a curved part expanding in a direction away from the main body. In a state where the plug is attached to the first opening, the curved part is pushed in a direction approaching the outer circumferential surface of the main body such that the curved part extends, thereby cancelling a loosely fitted state between the side wall and the outer circumferential surface, so as to remove the plug from the first opening end.
