A rotor for a motor includes a shaft having an outer periphery with an engaging portion. At least one coupling member includes an engaging hole. The shaft extends through the engaging hole of the at least one coupling member. The at least one coupling member is engaged with the engaging portion of the shaft by tight coupling. A plastic magnet envelops the shaft and the at least one coupling member by injection molding. The at least one coupling member prevents the plastic magnet from disengaging from the shaft, providing enhanced engaging effect while reducing structural complexity and enhancing assembling convenience.