A secure computation system in which a 0 +a 1 x 1 +...+a n x n is assumed to be an n-th order polynomial (n is an order of the polynomial and a 0, a 1,..., a n are coefficients of the polynomial) in a variable x, x is assumed to be a value which is substituted into the n-th order polynomial, k is assumed to be an integer which satisfies k ≤ x < k+1, r is assumed to be a random number which satisfies k ≤ r < k+1, and [[r]], [[r 2]],..., [[r n]], [[r-1]], [[(r-1) 2]],..., [[(r-1) n]] are assumed to be concealed text of a power of the random number r and a power of r-1, the secure computation system which is configured with two or more secure computation devices and calculates, from concealed text [[x]] of the value x, concealed text [[a 0 +a 1 x 1 +...+a n x n]] of values of the n-th order polynomial a 0 +a 1 x 1 +...+a n x n in which the value x is substituted, the secure computation system comprising: a comparing means that generates concealed text [[u]] of u (u = 1 if x ≤ r holds and u = 0 if x ≤ r does not hold), which is a result of magnitude comparison between the value x and the random number r, from the concealed text [[x]] by using the concealed text [[r]]; a mask means that generates concealed text [[c]] of a mask c as [[c]] = [[x]]-[[r]]+[[u]] from the concealed text [[x]], the concealed text [[r]], and the concealed text [[u]]; a reconstructing means that reconstructs the mask c from the concealed text [[c]]; a coefficient calculating means that calculates, for i = 0,..., n, a coefficient bi by a formula below from the order n, the coefficients a 0, a 1,..., a n, and the mask c; b i = ∑ j = i n a j j i c j − i a selecting means that generates, for i = 1,..., n, concealed text [[s i]] of a selected value s i (s i = (r-1) i if u = 1 and si = r i if u = 0), which is determined in accordance with the result u of magnitude comparison, from the concealed text [[u]]; and a linear combination means that calculates a linear combination b 0 +b 1 [[s 1]]+...+b n [[s n]] of the coefficient b i (i = 0,..., n) and the concealed text [[s i]] (i = 1,..., n) as the concealed text [[a 0 +a 1 x 1 +... + a n x n]]. a comparing means that generates concealed text [[u]] of u (u = 1 if x ≤ r holds and u = 0 if x ≤ r does not hold), which is a result of magnitude comparison between the value x and the random number r, from the concealed text [[x]] by using the concealed text [[r]]; a mask means that generates concealed text [[c]] of a mask c as [[c]] = [[x]]-[[r]]+[[u]] from the concealed text [[x]], the concealed text [[r]], and the concealed text [[u]]; a reconstructing means that reconstructs the mask c from the concealed text [[c]]; a coefficient calculating means that calculates, for i = 0,..., n, a coefficient bi by a formula below from the order n, the coefficients a 0, a 1,..., a n, and the mask c; b i = ∑ j = i n a j j i c j − i a selecting means that generates, for i = 1,..., n, concealed text [[s i]] of a selected value s i (s i = (r-1) i if u = 1 and si = r i if u = 0), which is determined in accordance with the result u of magnitude comparison, from the concealed text [[u]]; and a linear combination means that calculates a linear combination b 0 +b 1 [[s 1]]+...+b n [[s n]] of the coefficient b i (i = 0,..., n) and the concealed text [[s i]] (i = 1,..., n) as the concealed text [[a 0 +a 1 x 1 +... + a n x n]].