To provide a shock absorber that can effectively absorb a large amount of energy generated in case of a collision. A lattice body of synthetic resin is formed by reducing the thickness of a plurality of plate ribs gradually from the proximal ends to the distal ends and disposing the plate ribs intersecting with each other. The lattice bodies are arranged in a stack such that the direction of the plate ribs extending from the proximal ends toward the distal ends is oriented in an impact direction.