The purpose of the invention is to provide a rotor blade support structure, wherein the concentration of stress near the rotor blade groove in which the rotor blade is embedded is limited even as increase in production cost is limited. A rotor blade support structure, in which rotor blades (30) are embedded in rotor blade grooves (10) provided on a rotor disc (1), wherein the rotor blade groove (10) is provided with circular direction grooves (13) that extend more in the circular direction of the rotor disc than upward from the bottom (14), and shaft center direction grooves (15) that are provided on the end faces (1a, 1b) of the rotor disc (1) in the center of the bottom (14) in the circular direction of the rotor disc and that extend towards the rotor disc shaft center.