A plug connector includes a signal contact conductor to which an internal conductor of a coaxial cable is connected, a ground contact conductor to which an external conductor of the coaxial cable is connected, and an insulating housing that insulates the signal contact conductor from the ground contact conductor. The insulating housing includes an insulating main body in which the signal contact conductor is held and a protrusion that protrudes from a peripheral surface of the insulating main body in a radially outward direction of the insulating main body. The protrusion includes a base portion on which an insulator and the external conductor of the coaxial cable are placed and a pair of walls that are erected on the base portion and are disposed to interpose at least a tip of the external conductor therebetween.