Abstract: The present invention relates to a controllable pitch propeller capable of changing a blade pitch according to the sailing conditions of a ship and, specifically, to a controllable pitch propeller having an optimal hub-to-tip diameter ratio, the propeller being capable of reducing the size of a hub so as to have a high efficiency that is close to the propulsion efficiency of a fixed pitch propeller (FPP). In order to accomplish the aforementioned objective, the present invention relates a controllable pitch propeller which comprises a hub mounted at the propelling shaft of a ship, and a blade that is mounted at the circumference of the hub and that has a variable pitch, and which is technically characterized by a H/D ratio, of diameter (H) of the propeller and diameter (D) of the hub, of 0.170-0.2.