A similarity calculation system calculating the similarity between a first vector and a second vector using homomorphic encryption having homomorphic operations defined with respect to at least one multiplication and a plurality of additions obtains the similarity between the first and the second vectors by using the homomorphic operations to calculate the inner product of the first encrypted vector obtained by using a public key for the homomorphic encryption to encrypt a row corresponding to the value of a component of the first vector extracted from a weighted similarity table of the similarity between each component of the first and the second vectors and the second encrypted vector obtained by transforming the value of a component of the second vector into a component in a unit vector that becomes 1 and encrypting the transformed result with the public key for the homomorphic encryption.