To provide the decoding device which has a high operation speed, a small amount of hardware, and a low power consumption and can decode the bit string of a variable length code with plural bits as a unit at the time of reducing the number of cycles required for acquisition of the decoded result.

Correspondence tables between n-bit variable length codes and equal-length codes are stored in b storage devices 1, 2, 3... (b); and when an arbitrary input bit string is compared with correspondence tables to find a corresponding equal-length code, the found equal-length code and information indicating that it is found are outputted. When m bits are outputted, the storage device provided with the correspondence table between the variable length code of m or less bits and the equal-length code is selected; and when this storage device outputs information indicating that the equal-length code is found, the corresponding equal-length code is outputted.