Abstract: A hub motor unit for an electric bicycle may include a hollow shaft mounted at a bicycle frame, a shifting portion having an input element rotatably mounted at the hollow shaft and an output element, a driven sprocket mounted at the input element, a hub housing rotatably mounted at an exterior circumference of the input element, and having an interior circumference fixedly connected to the output element of the shifting portion and an exterior circumference connected to a wheel through a spoke, a hub cover rotatably mounted at the hollow shaft and coupled to the hub housing, a motor portion mounted between the hollow shaft and the input element in the hub housing and supplying torque to the shifting portion through the input element according to a control signal, and a shift control portion mounted on a shift shaft in the hollow shaft and controlling the shifting portion.