A first connector (2) includes a first connector main body configured from an outer tube (4) of a cylindrical shape, an inner tube of a cylindrical shape, and a hub (12) disposed at a proximal end portion of the outer tube (4), a hollow needle supported on the hub (12), a first sealing member supported on the inner tube, a coil spring serving as puncturing portion biasing means for biasing the first sealing member toward a distal direction, and a clamping member disposed upon the outer tube (4). Upon an inner periphery portion of the proximal end portion of the outer tube (4), a pawl (44) is formed so as to project to the inner side. In addition, upon an outer periphery portion of a large diameter portion (1212) of a main body portion (121) of the hub (12), a plurality of ratchet teeth (126) which are engageable with the pawl (44) of the outer tube (4) are formed so as to project toward the outer side. Accordingly, the rotation in only one of the forward and backward directions of the hub (12) is prevented.
