To provide an electric wire holder that has sufficient play suppression effect even with small insertion force and its electric wire holder receiving portion.

There is provided an electric wire holder 10 including an electric wire holder body 11, an electric wire holder cover body 12 covering the electric wire holder body, and a hinge 10H connecting the electric wire holder body and electric wire cover body, and holding a plurality of electric wires W between the electric wire holder body and electric wire holder cover body. Further, the electric wire holder includes lock mechanisms 11L, 12L locking the electric wire holder body and electric wire holder cover body at a non-hinge-side end of the electric wire holder 10, and includes a rotary shaft 11S on a side face on the non-hinge-side end of the electric wire holder, a connection portion of a hinge projecting from the electric wire holder while the electric wire holder body and electric wire holder cover body are locked. At an electric wire holder receiving portion 50U of a housing 50, a play preventive rib 50H is stood in contact with the hinge 10H.