The present disclosure provides a bit quantization method of an artificial neural network. This method may include: (a) of selecting one parameter or one parameter group to be quantized in the artificial neural network; (b) a bit quantizing to reduce the data representation size for the selected parameter or parameter group to a unit of bits; (c) of determining whether the accuracy of the artificial neural network is equal to or greater than a predetermined target value; and (d) repeating steps (a) to (c) when the accuracy of the artificial neural network is equal to or greater than the target value.