1. A computer-readable, non-transitory medium storing a program which, when executed by a computer, causes the computer to perform a process comprising: splitting a first character string and a second character string into words; acquiring information including a semantic attribute that represents a semantic nature of each of the words and a conceptual code that semantically identifies said each of the words, from a storage device; identifying a pair of the words having a common semantic attribute between the first character string and the second character string; comparing the conceptual codes of the specified pair of the words between the first character string and the second character string; and generating a comparison result between the first character string and the second character string based upon a comparison result of the conceptual codes, wherein the first character string is split into a first set of words and the second character string is split into a second set of words, wherein a first conceptual structure that represents a relationship among the first set of the words is generated from the first character string using a first set of conceptual codes, on the basis of the semantic attribute and a grammatical configuration of each of the first set of the words, and a second conceptual structure that represents a relationship among the second set of the words is generated from the second character string using a second set of conceptual codes, on the basis of the semantic attribute and a grammatical configuration of each of the second set of the words, and wherein a pair of the conceptual codes having a common semantic attribute and a common among-the-words relationship between the first character string and the second character string are identified.