A blood circuit connector (100) includes: a main body (110) having a cylindrical shape and provided with a first opening end (120) and a second opening end (130) a plug (140) having a bottomed cylindrical shape and detachably attached to the first opening end (120) and a connection part (150) configured to connect the main body (110) and the plug (140). The plug (140) includes a side wall (142) loosely fitted to an outer circumferential surface (111) of the first opening end (120) in a state where the plug (140) is attached to the first opening end (120). The connection part (150) includes a curved part (155) expanding in a direction away from the main body (110). In the attached state, the curved part (155) is pushed in a direction approaching the outer circumferential surface (111) of the main body (110) such that the curved part (155) extends, thereby cancelling a loosely fitted state between the side wall (142) and the outer circumferential surface (111), so as to remove the plug (140) from the first opening end (120).
