Disclosed is a magnetic gear apparatus including a rotational magnetic force generator configured to generate rotational magnetic force, a magnetic path creator having a hollow shape so as to be provided at an outer circumferential surface of the rotational magnetic force generator, the magnetic path creator being configured to create a magnetic path of the rotational magnetic force generated from the rotational magnetic force generator, and a rotor provided at an outer circumferential surface of the magnetic path creator, the rotor including permanent magnets provided at an inner circumferential surface thereof and being rotatable by the rotational magnetic force. The rotational magnetic force generator includes one or more pairs of alternately arranged N-pole units and S-pole units. A torque of the rotor may vary as the number of the N-pole units and the S-pole units is adjusted.