22. A non-transitory computer readable recording medium storing a similarity calculation program for obtaining similarity between media data and a query, the program causing a computer to execute: a function for calculating a single score a that shows similarity between the text query and second meta text of a second media data by comparing the text query with the second meta text, the second meta text including a plurality of words describing contents of the second media data; a function for calculating inter-media similarity that shows similarity between the first meta text of the first media data and the second meta text of the second media data by comparing the plurality of words of the first meta text of the first media data with the plurality of words of the second meta text of the second media data; a function for obtaining the similarity between the first media data and the text query by using the inter-media similarity and the single score, a function of creating meta text including the first meta text and the second meta text based on the first media data and the second media data, respectively, wherein the first meta text includes an error, and the second meta text includes fewer errors than the first meta text; a function of calculating a creating difficulty of a text that is same as the text query with the meta text creating device; a function of calculating the similarity between the first media data and the text query by using the inter-media similarity and the single scores of the second media data as well as the creating difficulty; a function of creating the meta text by using a dictionary; and a function of calculating the creating difficulty as large, when the text query is an unknown word that is not registered to the dictionary.
22. A non-transitory computer readable recording medium storing a similarity calculation program for obtaining similarity between media data and a query, the program causing a computer to execute: a function for calculating a single score a that shows similarity between the text query and second meta text of a second media data by comparing the text query with the second meta text, the second meta text including a plurality of words describing contents of the second media data; a function for calculating inter-media similarity that shows similarity between the first meta text of the first media data and the second meta text of the second media data by comparing the plurality of words of the first meta text of the first media data with the plurality of words of the second meta text of the second media data; a function for obtaining the similarity between the first media data and the text query by using the inter-media similarity and the single score, a function of creating meta text including the first meta text and the second meta text based on the first media data and the second media data, respectively, wherein the first meta text includes an error, and the second meta text includes fewer errors than the first meta text; a function of calculating a creating difficulty of a text that is same as the text query with the meta text creating device; a function of calculating the similarity between the first media data and the text query by using the inter-media similarity and the single scores of the second media data as well as the creating difficulty; a function of creating the meta text by using a dictionary; and a function of calculating the creating difficulty as large, when the text query is an unknown word that is not registered to the dictionary. 29. The non-transitory computer readable recording medium storing the similarity calculation program as claimed in claim 22 , which enables the computer to execute a function of creating the meta text by converting the text data into a text of a same language as that of the text query by automatic translation by using the media data that is text data expressed with a language different from that of the text query.