PURPOSE: To reproduce sound with high quality at a low bit rate and with simple processing by setting the number of bits of a code data in a relevant block corresponding to a scale data.

CONSTITUTION: A scale setting section 5 identifies the largest absolute value among 8 consecutive samples of digital signals DS, discriminates the most significant digit of the bit pattern and outputs a bit location of the high-order by one bit in a 3-bit scale data DK. A compression section 4 takes a scale location represented by a scale data DK at each sample as the MSB and extracts a data in the number of bits of corresponding to a bit number data BD fed from a code bit number setting section 6 and uses it as the comparession data DC to supply an output to a data synthesis section 7. The data synthesis section 7 arranges the scale data DK as the head and a signal constituted by arranging each sample of compression data DC sequencially in succession thereto is used as a one block coded data DL. Thus, the sound with high quality is reproduced.