A searching device converts a searching data into an encoded searching data in a first encoding format according to a first encoding rule; and searches the encoded searching data in a target encoded data that has been encoded into the first encoding format by the first encoding rule, or that has been encoded in a second encoding format wherein when a specific encoded data encoded in the second encoding format is detected in the searching, the searching compares the encoded searching data and a converted encoded data, the converted encoded data being the specific encoded data converted into the first encoding format based on a predetermined conversion rule.