To increase the stroke in a plateau area when an impact load is applied, while securing the supporting rigidity of an impact energy absorber.

The impact energy absorber 1 has a metal bulk 2, a metal cylindrical body 3, and an easily collapsible material 4. The metal bulk 2 assumes a circular cylindrical shape or a polygonal cylindrical shape and includes a plurality of voids. The metal cylindrical body 3 assumes a polygonal cylindrical shape or a circular cylindrical shape covering the outer peripheral surface of the metal bulk 2, outwardly contacts the outer peripheral surface of the metal bulk 2, and has an inner peripheral surface forming a plurality of void parts between the same and the outer peripheral surface. The void part between the outer peripheral surface of the metal bulk 2 and the metal cylindrical body 3 are filled with the easily collapsible material 4.