A connector is disclosed, which includes a main body and a valve body. The main body can include a main line flow channel capable of circulating an infusion solution, and valve body arrangement portions and connecting to the main line flow channel. The valve body includes an operable and closable slit provided to a deformed portion. The valve body is provided along an opening/closing direction of the slit, and includes a guide portion configured to facilitate opening and closing of the slit, and a thickened portion protrusively formed so as to extend through near both ends in a longitudinal direction of the slit and on both sides of the guide portion.