A normalized activity calculating unit calculates a normalized activity that is calculated from luminescence component pixel values of an original image on the basis of information from an information buffer, such as bit rate, an amount of bits generated in each frame, and an amount of bits generated and a quantization step size in each macroblock. The normalized activity calculating unit then outputs the normalized activity to a code amount control unit. The code amount control unit calculates a quantization scale code corresponding to a target bit rate, which quantization scale code matches visual characteristics, using the normalized activity inputted from the normalized activity calculating unit, and then outputs the quantization scale code to a quantizing unit. The quantizing unit quantizes discrete cosine transform coefficients inputted from a band limiting unit on the basis of the quantization scale code inputted to the quantizing unit.