1. A data converting apparatus comprising: a storage unit that stores encoded meta-definition information that assigns a metadata code as a unique code to an element making up metadata in meta-definition information that defines metadata indicative of a property related to data of a conversion source and a conversion destination, a data converting function that converts conversion source data having a property prescribed by the metadata for the conversion source into conversion destination data having a property prescribed by the metadata for the conversion destination, a conversion rule table that assigns the data converting function according to a combination of a metadata code for the conversion source and a metadata code for the conversion destination, and a conversion rule that correlates with each of the conversion rule tables, a relevant metadata code as a conversion rule code; an input unit that receives input of data to be converted; a detecting unit that refers to the encoded meta-definition information stored in the storage unit and detects the metadata codes for the conversion source and the conversion destination for which the conversion rule code matches between the conversion source and the conversion destination; a determining unit that determines whether the detected metadata codes for the conversion source and for the conversion destination match; a converting function specifying unit that, by referring to a conversion rule stored in the storage unit and based on the determination result obtained by the determining unit, specifies the data converting function, according to the combination of the metadata code for the conversion source and the metadata code for the conversion destination; and a converting unit that, by using the data converting function specified by the converting function specifying unit, converts the conversion source data, which is the data to be converted, to have a property prescribed by metadata for the conversion destination.