A device for calculating a multi-turn absolute rotation angle, comprising: a transmission mechanism adapted to transmit revolution from a first rotating shaft of first to nmax-th rotating shafts down to the nmax-th rotating shaft, wherein a rotation angle θ n of an n-th rotating shaft satisfies the following relationship with a rotation angle θ 1 of the first rotating shaft: θ n = − m ± 1 m n − 1 × θ 1, where numerical values nmax and m are integers not less than 3 and a numerical value n falls within the range 1 ≤ n ≤ nmax; an angle detector adapted to detect angle detected values p 1 to p nmax within one revolution of the first rotating shaft to the nmax-th rotating shaft; and a computing unit adapted to calculate a multi-turn absolute rotation angle calculated value θ 1 (m nmax-1)' of the first rotating shaft on the basis of the angle detected values p 1 to p nmax, wherein the computing unit sequentially determines values of a coefficient R 0 to a coefficient R nmax-2 by repeating, for the numerical value n = 2 to nmax, a process of determining a coefficient R n-2 from a rotation angle calculated value θ 1 (m n-2)' and the angle detected value p n of the n-th rotating shaft and calculating a rotation angle calculated value θ 1 (m n-1)' by a rotation angle calculation formula: θ 1 m n − 1 ' = p 1 + ∑ i = 2 n R i − 2 × m i − 2 × u on the basis of the determined coefficient R n-2 and obtains the multi-turn absolute rotation angle calculated value θ 1 (m nmax-1)' of the first rotating shaft, the coefficients R 0 to R nmax-2 are integers ranging from 0 to m-1 inclusive, u is a base unit quantity, and a rotation angle calculated value θ 1 (m 0)' is the angle detected value p 1 of the first rotating shaft. a transmission mechanism adapted to transmit revolution from a first rotating shaft of first to nmax-th rotating shafts down to the nmax-th rotating shaft, wherein a rotation angle θ n of an n-th rotating shaft satisfies the following relationship with a rotation angle θ 1 of the first rotating shaft: θ n = − m ± 1 m n − 1 × θ 1, where numerical values nmax and m are integers not less than 3 and a numerical value n falls within the range 1 ≤ n ≤ nmax; an angle detector adapted to detect angle detected values p 1 to p nmax within one revolution of the first rotating shaft to the nmax-th rotating shaft; and a computing unit adapted to calculate a multi-turn absolute rotation angle calculated value θ 1 (m nmax-1)' of the first rotating shaft on the basis of the angle detected values p 1 to p nmax, wherein the computing unit sequentially determines values of a coefficient R 0 to a coefficient R nmax-2 by repeating, for the numerical value n = 2 to nmax, a process of determining a coefficient R n-2 from a rotation angle calculated value θ 1 (m n-2)' and the angle detected value p n of the n-th rotating shaft and calculating a rotation angle calculated value θ 1 (m n-1)' by a rotation angle calculation formula: θ 1 m n − 1 ' = p 1 + ∑ i = 2 n R i − 2 × m i − 2 × u on the basis of the determined coefficient R n-2 and obtains the multi-turn absolute rotation angle calculated value θ 1 (m nmax-1)' of the first rotating shaft, the coefficients R 0 to R nmax-2 are integers ranging from 0 to m-1 inclusive, u is a base unit quantity, and a rotation angle calculated value θ 1 (m 0)' is the angle detected value p 1 of the first rotating shaft.