The impact shock absorbing structure has a protector including a front underrun protector attached to the body frame of the vehicle by means of brackets, the structure being strong enough against the impact shock and flexible to lessen the impact shock in order to be capable of preventing the occurrence of breakage due to the impact shock. The structure is provided with a protector(12) at the front or rear end of the body frame(100) of the vehicle for receiving the impact shock when the vehicle collided with an opponent car(200), wherein the bracket(1) has a body frame attaching part(3) for attaching to the body frame(100); a protector attaching part(4) for attaching to the protector(12); and a connecting plate part(5) for connecting the body frame attaching part(3) and protector attaching part(4), the connecting plate part(5) extending in the vertical and longitudinal direction of the vehicle; and wherein the connecting plate part(5) has a cut-out part(2) opening frontward or rearward of vehicle, and the protector attaching part(4) is located in the position lower than the cut-out part(2).