A connector (10) includes, in a main body (38), first to third ports (24, 26, 28) each having a flow channel allowing inflow or outflow of an infusion solution, an internal flow channel (52) configured to communicate between flow channels of the first port (24) and the second port (26), and a through hole (76) connected to an internal flow channel (52). On the internal flow channel (52), an upstream side wall surface (92) is provided which guides infusion solution flowing into the internal flow channel (52) from the first port (24) to the through hole (76), and reduces the cross-sectional area of the flow channel for the infusion solution near the through hole (76) relative to the cross-sectional area of the flow channel of the first port (24).
