A front end of a left member having a first plate thickness, and a left end of a lateral member having a third plate thickness are welded together while defining a first weld line, and a front end of a right member having a second plate thickness and a right end of the lateral member are welded together while defining a second weld line. The first plate thickness and the second plate thickness are thinner than the third plate thickness, and a support bracket that supports an auxiliary equipment is fitted to the lateral member. The first weld line and the second weld line are respectively positioned outer side of the vehicle body with respect to a fitted position of the support bracket, so as not to overlap on the fitted position in the lateral member where the support bracket is fitted to the lateral member.