To provide a method for decoding a cyclic code and a decoding circuit in which a coefficient calculation circuit of an error position multinomial equation Λ (Z) is the same, a repetition count of a calculation loop is always a fixedcount, and a condition determination is small, in the method for decoding a cyclic code and the decoding circuit in which t-piece or less of error is correctable. t個以下の誤りを訂正可能な巡回符号の復号方法および復号回路であって、誤り位置多項式Λ(Z)の係数計算回路が同一、かつ演算ループの繰り返し回数が常に一定回数、かつ条件判断が少ない巡回符号の復号方法および復号回路を提供する。 - 特許庁