Provided is an encoding/decoding technique according to which it is possible to perform encoding with a small average bit count, even for a series of integer values with a distribution that is significantly biased to a small value, including small values that are not zero values. The present invention includes an integer encoding unit that, for an input series of non-negative values xn, n∈{1, 2, . . . , N} (hereinafter referred to as “integer series”), obtains a one-bit code with a bit value of “x” as a code corresponding to L consecutive integer values 0 included in the integer series, L being an integer that is 2 or more, and obtains a K×xn-bit or a K×xn+1-bit code that includes at least one bit value “x” and at least one bit value “y” in the first bit to the K-th bit and in which the bit values of the K×(xn−1) bits from the end are “y”, as a code corresponding to a set composed of 0 to L−1 consecutive integer values 0 included in the integer series and one integer value xn other than 0.