An apparatus for controlling a motor determines whether or not to control the motor in order to control the variable valve lift device by using a measurement value of a valve lift and a target value of the valve lift, compares a predetermined base voltage range with a battery voltage in order to control the motor, determines a voltage factor corresponding to the battery voltage when the battery voltage is included in the base voltage range; and determines a driving signal value for the motor by applying the voltage factor to a predetermined base signal value.