PURPOSE: To prevent the increase in processing time and to reduce generation code amount while restricting the deterioration of a picture quality between an original picture and a decoded picture by making a quantization coefficient zero against a frequency area with a variable threshold value.

CONSTITUTION: The device is provided with a threshold value generation means 107 obtaining the average value of the absolute value of the coefficient for non-zero from among quantization coefficients by a factor of constant for each frequency area according to the frequency area and obtaining the threshold values for each frequency area and a threshold value discrimination means 108 comparing the threshold value of the output of the threshold value generation means 107 and the absolute value of the quantization coefficient for each frequency area to be outputted as it is when the absolute value of the coefficient is more than the threshold value and to be outputted by making it zero when less than the threshold value.