PURPOSE: To secure a stable regenerative band width and to prevent noise generation by determining the band width of each block by making reference to the band width determined by the use of the precedent block.

CONSTITUTION: Normalization constant information supplied from a normalization circuit 61 is sent to a quantization precision determining circuit 64 and a control circuit 63. The circuit 63 determines the number of regenerative coding units in the block being processed based on the information on the number of reproducible coding units sent from the quantization precision determining circuit 64 and the information on the reproducible coding units and information on the normalization factor sent from the bandwidth storage circuit 62. Next, the control circuit 63 feeds the information on the determined regenerative coding units and the control signals to the quantization precision determining circuit 64. The circuit 64 reallots the bits allotted to the coding unit on the high frequency side to the inside of the coding unit of the determined number of the regenerative coding units to determine the ultimate bit allotment.