PURPOSE: To provide a structure by which input load to a side member at collision can be efficiently transmitted to a side sill through matching of fit receiving faces and fit pressing faces, so as to improve energy absorbing charac teristic at collision.

CONSTITUTION: A front side member 25 is provided with fit abutting faces 61X, 61Z, 63X, 63Z, 65X, 65Z to be joined to a side sill 27 in the right and left direction and the up and down direction of the closed sectional part 59. Meanwhile, the side sill 27 is provided with fit receiving faces 81X, 81Z, 83X, 83Z, 85X, 85Z respectively in response to these fit abutting faces 61X, 61Z, 63X, 63Z, 65X, 65Z. The stress to the front side member 25 at collision of the front of a vehicle is stably and efficiently transmitted from the front member 25 to the side sill 27 while restraining partial deformation through matching of the fit receiving faces and the fit abutting faces. Hereby, energy absorbing characteristic at collision is improved and rigidity of the whole body is improved.