PURPOSE: To omit oil leak preventing seal by forming a continuously variable transmission to which a fixed cam plate is surely fixed

CONSTITUTION: An engagement member 12 for preventing rotation of a fixed cam plate 11 around the rotational shaft center Y of a rotational member 8 forming a hydraulic motor M, is provided on the inner surface of a case 1, while a regulating member 13 for preventing connection of the displacement in which the fixed cam plate 11 is to be separated from the inner surface of the case along the rotational shaft core Y of the rotational member 8, is mounted on the inner surface of the case 1.