In an encoding apparatus, when difference value between adjacent quantization units of quantization accuracy information where, e.g., distribution range is 0 SIMILAR 7, e.g., if difference value is 3 or more, 8 is subtracted, and if difference value is less than -4, 8 is added to thereby transform two difference values where difference therebetween is 8 into the same value. Thus, the distribution range of difference value becomes -4 SIMILAR 3, and size of code book (table) can be held down to the same size in the case where difference is not taken. In addition, high order 1 bit of difference value may be masked to carry out replacement into value consisting of only low order 3 bits, thus also making it possible to prevent increase in size of code book (table).