To provide a small electric connector having a lock mechanism with excellent hardness.

A metal reinforcement plate 6 comprises: a main body 22 having a fixing piece 21 fixed to a corresponding side part in a housing; a lock lever of a cantilever form extended from the main body 22 in a direction X2 opposite to an insertion direction X1 of a connecting member; and a leg 26 which is extended from the main body 22 and soldered to a conductive part of a substrate. The main body 22, the lock lever 25 and the leg 26 are integrally formed by a single material. A base end 28 of the lock lever 25 is connected to the main body 22, and an operation unit 30 is provided at an end 29. By engaging with a recess provided in the side part of the connecting member, an engaging projection 32 to prevent slipping off of the connecting member from an insertion groove is formed at an intermediate part 31 of the lock lever 25.