Overlapping section (81) is constructed by positioning an inner side wall portion (78) of an outer impact absorbing section (63) closer to a longitudinal centerline (48) of a vehicle body than an outer side wall (33, 103) of a front side frame (11, 12; 91), so that a collision impact load can be transmitted to the outer side wall portion by way of the overlapping section. Inner impact absorbing section (62) projects forward by a greater length than an outer impact absorbing section (63). Thus, an airbag- deploying acceleration threshold value Gs is set within a range between an acceleration level when the inner impact absorbing section (62) alone is deformed by impact energy and an acceleration level when the inner and outer impact absorbing sections (62, 63) are deformed.