The present disclosure relates to a neuromorphic arithmetic device. The neuromorphic arithmetic device may include first and second synapse circuits, a charging/discharging circuit, a comparator, and a counter. The first synapse circuit may generate a first current by performing a first multiplication operation on a first PWM signal and a first weight, and the second synapse circuit may generate a second current by performing a second multiplication operation on a second PWM signal and a second weight. The charging/discharging circuit may store charges induced by the first current and the second current in a charging period, and may discharge the charges in a discharging period. The comparator may compare a voltage level of the charges discharged in the discharging period and a level of a reference voltage. The counter may count output pulses of an oscillator on the basis of a result of the comparison by the comparator.