A first connector is provided and includes a first connector body having a cylindrical outer tube, a cylindrical inner tube, and a hub a hollow needle supported by the hub a first sealing member supported by the inner tube a coil spring that biases the hub in a proximal direction and biases the first sealing member in the distal direction and gripping and pressing members disposed on the outer tube. A plurality of pawls are formed on a flange of the hub. A plurality of ratchet teeth are formed on an inner circumferential portion of a proximal portion of the outer tube. Each of the ratchet teeth and each of the pawls of the hub form an engagement-disengagement mechanism.
