PROBLEM TO BE SOLVED: To provide an electric connector with a simple structure capable of successfully holding and separating a signal transmission medium PB inserted into the inside of a connector body part 11.SOLUTION: A lock part 14 for maintaining an inserted condition by engaging with a part of a signal transmission medium PB inserted into the inside of a connector body part 11, is provided on a tip of an elastically displaceable cantilever lock arm member 14a integrally formed with a board connection leg part (hold down) 13b, and an elastic action by the lock arm member 14a extending relatively long in a direction from a swing support point 14d, successfully maintains a holding condition of the signal transmission medium and reduces a release operation force for the lock part 14, simultaneously. The strength can be enhanced by stably receiving the release operation force for the lock part 14 by the board connection leg part (hold down) held on a printed wiring board.