An arithmetic device includes an input distribution signal generation circuit, an output distribution signal generation circuit, and an output distribution signal compensation circuit. The input distribution signal generation circuit generates an input distribution signal and a compensation signal based on an arithmetic result signal generated from a result of a multiplying-accumulating (MAC) calculation. The output distribution signal generation circuit applies the input distribution signal to an activation function to generate first and second output distribution signals. The output distribution signal compensation circuit compensates for the first output distribution signal based on the compensation signal, the first output distribution signal, and the second output distribution signal to generate a compensated distribution signal.