To provide an image encoding device which can efficiently encode a coefficient represented as a complement of 2 with a small circuit scale.

The image encoding device comprises a means of converting a coefficient input value represented as a signed complement of 2 into an absolute value and a sign bit, a quantizing process means of performing a quantizing process or quantization scaling process for the coefficient as the absolute value outputted from the converting means and outputs a quantization coefficient as the absolute value, a priority encoder which finds a category from the output of the quantizing process means, a bit inverting means of finding the bit inverted value of the quantization coefficient as the absolute value, a selecting means of selecting and outputting the output of the bit inverting means or the quantization coefficient as the absolute value according to the value of the sign bit, a decoder which generates a mask pattern for masking the output of the priority encoder other than effective bits, and a mask means which generates position information in the category by masking the output of the selecting means by using the mask pattern outputted by the decoder.