A resin impact energy absorber for vehicle having a single wall solid plate structure, the resin impact energy absorber comprising: a peripheral wall; a planar portion surrounded by the peripheral wall; and a plurality of first protrusions, the first protrusions being parallel to one another at a predetermined interval in the planar portion, wherein the first protrusion includes: a pair of inclined vertical walls that projects from the planar portion, the inclined vertical walls facing one another; and a top wall that couples tops of the pair of inclined vertical walls with one another at approximately the same height as the peripheral wall; the pair of inclined vertical walls is inclined at a predetermined inclination angle such that the pair of inclined vertical walls comes close to one another as approaching from the planar portion to the top wall, the planar portion includes one plate surface and another plate surface, at least one of the one plate surface and the other plate surface including an impact load receiving surface; characterised in that the resin impact energy absorber further comprises a second protrusion that extends in a direction intersecting with the plurality of first protrusions in the planar portion; wherein the second protrusion couples the peripheral wall with the inclined vertical wall of the first protrusion closest to the peripheral wall, and couples the inclined vertical walls of the adjacent first protrusions with one another, the second protrusion has a protrusion height lower than a protrusion of the plurality of first protrusions; and the second protrusion is coupled with the first protrusions at root portions. a peripheral wall; a planar portion surrounded by the peripheral wall; and a plurality of first protrusions, the first protrusions being parallel to one another at a predetermined interval in the planar portion, wherein the first protrusion includes: a pair of inclined vertical walls that projects from the planar portion, the inclined vertical walls facing one another; and a top wall that couples tops of the pair of inclined vertical walls with one another at approximately the same height as the peripheral wall; a pair of inclined vertical walls that projects from the planar portion, the inclined vertical walls facing one another; and a top wall that couples tops of the pair of inclined vertical walls with one another at approximately the same height as the peripheral wall; the pair of inclined vertical walls is inclined at a predetermined inclination angle such that the pair of inclined vertical walls comes close to one another as approaching from the planar portion to the top wall, the planar portion includes one plate surface and another plate surface, at least one of the one plate surface and the other plate surface including an impact load receiving surface; characterised in that the resin impact energy absorber further comprises a second protrusion that extends in a direction intersecting with the plurality of first protrusions in the planar portion; wherein the second protrusion couples the peripheral wall with the inclined vertical wall of the first protrusion closest to the peripheral wall, and couples the inclined vertical walls of the adjacent first protrusions with one another, the second protrusion has a protrusion height lower than a protrusion of the plurality of first protrusions; and the second protrusion is coupled with the first protrusions at root portions.