Computations to determine the quantized DCT coefficient are repeated to reduce the parameter number of the DCT coefficient.

Upon reception of the control signal, the image information modification unit (213) modifies image information (quantized DCT coefficient), is output to a variable length encoding unit (208), and output to a reverse quantization unit (209).

The quantized DCT coefficient before the variable-length coding is counted by a counter unit (21), while the code quantity of the variable-length coded macro block information is counted by a counter unit (14).

In the image encoding apparatus; a synchronous word containing possibility detection unit (212) decides whether a quantized DCT coefficient can be a bit string to become a synchronous word.

When the possibility of containing a synchronous word is not detected, the quantized DCT coefficient is output to the variable length encoding unit (208) and output to the reverse quantization unit (209).