PURPOSE: To reduce an inertial load applied to a passenger at the time of belly landing of an aircraft.

CONSTITUTION: This device is constituted of a floor plate supported to a fuselage free to move in the longitudinal direction, a shear pin connecting a constitutional member of the fuselage and the floor plate to each other and a spring 11 interposed in the longitudinal direction between the constitutional member of the fuselage and the floor plate 3, and at the time when an inertial load is added at the time of belly landing and others, the shear pin is cut off, the floor plate 3 moves forward against the spring 11 and the inertial load added to a passenger is buffed.