An impact absorbing member 10 able to secure absorption energy while lightening weight by absorbing the impact load applied in the axial direction by periodic buckling, wherein the impact absorbing member 10 is provided with a main body 20 comprised of metal sheet and having a polygonal shape in cross-section vertical to an axial direction and a center sheet 30 comprised of metal sheet and provided at a hollow part in the main body along the axial direction, the polygonal shape of the main body 20 includes a pair of long side (20a, 20b) facing each other, the center sheet 30 is joined to each of the long sides (20a, 20b) of the polygonal shape of the main body 20, and the sheet thickness t1 (mm) of the main body 20 and the sheet thickness t2 (mm) of the center sheet 30 satisfy 1.3×t1‰¤t2.