To provide an electric connector assembly with improved total mechanical and electrical performances which guarantees an effect of a stable insertion fitting of connectors in contact with each other and has a function of grounding connection.

The electric connector assembly includes a first connector and a second connector. The first connector is provided with a first terminal and a first insulation main body containing the first terminal. A first ear part for mounting a first elastic piece is extended from both end parts in the length direction of the first insulation main body, and the first elastic piece is equipped with a first elastic part, to which an arc-shape protrusion is fitted. The second connector is provided with a second terminal and a second insulation main body containing the second terminal. A second ear part for mounting a second elastic piece is extended from both end parts in the length direction of the second insulation main body, and the second elastic piece is equipped with a second elastic part, to which is fitted a locking groove for engaging itself with the arc-shape protrusion.