A mean rate decision method for a clutch motor is disclosed. The method includes determining whether the clutch motor and a gear sensor are in an electrical failure state; when it is determined the clutch motor and the gear sensor are not in the electrical failure state, determining whether there is a driver's starting intention on the basis of state information on the clutch pedal; setting a target position of the clutch motor according to a pedal setting value set by the clutch pedal; and when it is determined that there is no driver's starting intention and that an actual position of the clutch motor exceeds the target position of the clutch motor, determining a failure of the clutch motor on the basis of an excess movement amount and an excess duration in the excess state.