Propellant force generator

A propellant force generator is provided having the size in the axial direction of a rotational shaft of a motor reduced while making the pitch angles of rotational blades driven by the motor variable. The propellant force generator includes a propellant-force generating motor adapted to generate a propellant force for rotational blades, a pitch varying motor adapted to generate a rotational motion for changing pitch angles of the rotational blades, a rotation-linear motion converting unit adapted to convert the rotational motion generated by the pitch varying motor into a linear motion, and a linear motion-rotation converting unit adapted to convert the linear motions converted by the rotation-linear motion converting unit into rotational motions. At least a part of the linear motion-rotation converting unit is located within the propellant-force generating motor.