An additive manufactured object according to at least one embodiment of the present disclosure includes a first base portion made of a metal, and a plurality of wall portions each having a thickness thinner than the first base portion and provided upright on the first base portion so as to be aligned in a wall thickness direction. A first end portion of each of the wall portions is connected to the first base portion via a first connection portion having a width greater than the thickness of each of the wall portions in the wall thickness direction.