there are provided a signal duty detecting apparatus detecting a duty of a pulse width modulation signal by counting a signal , among signals present in a preset period of the pwm signal , having a predetermined level or higher and a motor driving apparatus having the same . the signal duty detecting apparatus includes : a level detector detecting levels of an input signal ; a counter counting the levels detected by the level detector ; and a duty calculator calculating a duty of the input signal based on the levels counted by the counter .