A computation apparatus that is used in performing a sum-of-product computation by three computation apparatuses in cooperation, the three computation apparatuses serving as a party X, a party Y and a party Z and performing symmetric processings, wherein provided that any of the computation apparatuses is a party P, it is assumed that the party Z is a party P -, and the party Y is a party P +, and subscripts 0p, 1p and 2p are 0, 1 and 2, respectively, if the party P is the party X, the party X is the party P -, the party Z is the party P +, and the subscripts 0p, 1p and 1p are 1, 2 and 0, respectively, if the party P is the party Y, and the party Y is the party P -, the party X is the party P +, and the subscripts 0p, 1p and 2p are 2, 0 and 1, respectively, if the party P is the party Z, m represents an integer equal to or greater than 1, na0p, na1p, na2p, nb0p and nb1p represent natural numbers, q = 0,..., m-1, i0p = 0,..., na0p-1, i1p = 0,..., na1p-1, i2p = 0,..., na2p-1, j0p = 0,..., nb0p-1, and j1p = 0,..., nb1p-1, and e0p1p i0p,j1p, e1p0p i1p,j0p, e0p0p i0p,j0p and e1p1p i1p,j1p represent any numbers, characterized in that said party P comprises: first random number generation means (101, 301) adapted to generate a number r q_P and transmit the number to the party P +; first computation means (102, 302) adapted to receive data strings A q_0p = (a0p q_0,..., a0p q_na0p-1), A q_1p = (a1p q_0,..., a1p q_na1p-1), B q_0p = (b0p q_0,..., b0p q_nb0p-1) and B q_1p = (b1p q_0,..., b1p q_nb1p-1), compute a value c q_P according to c q_P = ∑ q_i ⁢ 0 ⁢ p, q_j ⁢ 1 ⁢ p e ⁢ 0 ⁢ p ⁢ 1 ⁢ p q_i ⁢ 0, q_j ⁢ 1 ⁢ p ⋅ a ⁢ 0 ⁢ p q_i ⁢ 0 ⁢ p ⋅ b ⁢ 1 q_j ⁢ 1 ⁢ p + ∑ q_i ⁢ 1, q_j ⁢ 0 ⁢ p e ⁢ 1 ⁢ p ⁢ 0 ⁢ p q_i ⁢ 1, q_j ⁢ 0 ⁢ p ⋅ a ⁢ 1 ⁢ p q_i ⁢ 1 ⁢ p ⋅ b ⁢ 0 ⁢ p q_j ⁢ 0 ⁢ p + r q_P, and transmit the value to the party P -; and second computation means (103, 303) adapted to receive a number r q_P- from the party P -, a value c q_P+ from the party P +, compute values c q_0p and c q_1p according to c q_ 0 ⁢ p = ∑ q_i ⁢ 0 ⁢ p, q_j ⁢ 0 ⁢ p e ⁢ 0 ⁢ p ⁢ 0 ⁢ p q_i ⁢ 0 ⁢ p, q_j ⁢ 0 ⁢ p ⋅ a ⁢ 0 ⁢ p q_i ⁢ 0 ⁢ p ⋅ b ⁢ 0 ⁢ p q_j ⁢ 0 ⁢ p + c q_P - r q_P c q_ 1 ⁢ p = ∑ q_i ⁢ 1 ⁢ p, q_j ⁢ 1 ⁢ p e ⁢ 1 ⁢ p ⁢ 1 ⁢ p q_i ⁢ 1 ⁢ p, q_j ⁢ 1 ⁢ p ⋅ a ⁢ 1 ⁢ p q_i ⁢ 1 ⁢ p ⋅ b ⁢ 1 ⁢ p q_j ⁢ 1 ⁢ p + c q_P + - r q_P. first random number generation means (101, 301) adapted to generate a number r q_P and transmit the number to the party P +; first computation means (102, 302) adapted to receive data strings A q_0p = (a0p q_0,..., a0p q_na0p-1), A q_1p = (a1p q_0,..., a1p q_na1p-1), B q_0p = (b0p q_0,..., b0p q_nb0p-1) and B q_1p = (b1p q_0,..., b1p q_nb1p-1), compute a value c q_P according to c q_P = ∑ q_i ⁢ 0 ⁢ p, q_j ⁢ 1 ⁢ p e ⁢ 0 ⁢ p ⁢ 1 ⁢ p q_i ⁢ 0, q_j ⁢ 1 ⁢ p ⋅ a ⁢ 0 ⁢ p q_i ⁢ 0 ⁢ p ⋅ b ⁢ 1 q_j ⁢ 1 ⁢ p + ∑ q_i ⁢ 1, q_j ⁢ 0 ⁢ p e ⁢ 1 ⁢ p ⁢ 0 ⁢ p q_i ⁢ 1, q_j ⁢ 0 ⁢ p ⋅ a ⁢ 1 ⁢ p q_i ⁢ 1 ⁢ p ⋅ b ⁢ 0 ⁢ p q_j ⁢ 0 ⁢ p + r q_P, and transmit the value to the party P -; and second computation means (103, 303) adapted to receive a number r q_P- from the party P -, a value c q_P+ from the party P +, compute values c q_0p and c q_1p according to c q_ 0 ⁢ p = ∑ q_i ⁢ 0 ⁢ p, q_j ⁢ 0 ⁢ p e ⁢ 0 ⁢ p ⁢ 0 ⁢ p q_i ⁢ 0 ⁢ p, q_j ⁢ 0 ⁢ p ⋅ a ⁢ 0 ⁢ p q_i ⁢ 0 ⁢ p ⋅ b ⁢ 0 ⁢ p q_j ⁢ 0 ⁢ p + c q_P - r q_P c q_ 1 ⁢ p = ∑ q_i ⁢ 1 ⁢ p, q_j ⁢ 1 ⁢ p e ⁢ 1 ⁢ p ⁢ 1 ⁢ p q_i ⁢ 1 ⁢ p, q_j ⁢ 1 ⁢ p ⋅ a ⁢ 1 ⁢ p q_i ⁢ 1 ⁢ p ⋅ b ⁢ 1 ⁢ p q_j ⁢ 1 ⁢ p + c q_P + - r q_P.