A commutator has a conductive layer, a segment layer and an insulating layer separating the conductive layer and the segment layer. The segment layer includes multiple commutator segments. A mounting hole is defined along an axis of the commutator passing through the conductive layer. The three-layer structure of the commutator forms a capacitor having an increased confronting area and reduced inter-plate distance. The capacitor thus has a greater capacitance and hence greater EMI absorbing capability, making it possible to reduce EMI emissions without additional EMI reduction components outside the commutator. A rotor and a motor employing the commutator are also disclosed.