Abstract: Provided is a connector including a plug to be fixed to an inner peripheral surface of an opening of a liquid storing container, and a socket to be detachably attached to the plug. The plug includes a plug body in which a first liquid outflow passage, a first liquid inflow passage, and a first gas passage are formed. The socket includes a socket body including, formed therein, a second liquid outflow passage, a second liquid inflow passage), and a second gas passage; a rotary valve having an outflow through-hole and an inflow through-hole; and a switching mechanism for switching between an open state and a closed state when the rotary valve is rotated.