To provide core supporting structure with which molten metal can be supplied at high speed into a mold cavity with a cantilevered core arranged therein without breaking the core, and to provide a casting method.

The core supporting structure 9 is provided with: the cantilevered core 10 with the base part supported at the cavity surface of the cavity 5 in the mold 2; and a sliding member 11 which is disposed in a manner of passing through the cantilevered core 10 and is slidable toward the base part from the distal end part of the cantilevered core 10 while the outer circumferential surface of the sliding member abuts on the cavity surface of the cavity 5 in the mold 2. The core supporting structure 9 is arranged in the cavity 5 in the mold 2 and the sliding member 11 is disposed at the position corresponding to the distal end part of the cantilevered core 10, and molten metal 8 is supplied into the cavity 5 in the mold 2.