Piston casting method and piston casting device

A piston casting device for casting a piston comprising a columnar ring land part having a top wall, a pair of skirt parts extending downward from opposite end parts, in a diameter direction, of the ring land part, a pair of side wall parts extending from a lower face of the ring land part and linking opposite ends of the two skirt parts to each other, and a pair of pin boss parts formed on these side wall parts, a pair of cutout recess parts being provided in the lower face of the ring land part, an outside face of the side wall part facing the cutout recess parts, and an inside face in a radially outward direction of the cutout recess part being inclined in a direction away from a central axis of the piston in going downward,

• wherein the piston casting device comprises a pair of main molds that open and close along a path in a transverse direction orthogonal to the central axis of the piston in order to form an outer peripheral face of the piston, a guide member having a pair of guide faces that are inclined in a direction away from the central axis of the piston in going downward, a pair of core support bodies having in upper parts a pair of side cores forming the pair of cutout recess parts, and a core raising and lowering device that makes the core support bodies ascend and descend along the pair of guide faces between a set position of the side core where the cutout recess part is to be formed and a mold release position where the side core is released from the cutout recess part, and the core raising and lowering device is arranged so that, when the core support body is made to descend from the set position to the mold release position, the core support body is tilted in a direction in which an upper end of the side core approaches the central axis of the piston.