This paper performs cost evaluation of storageindependent SPARQL-to-SQL use model. With development of Semantic Web, much research focuses on various technologies about Web ontology. Especially, for management and searching of data in Web ontology, various storages based on RDB and query languages (e.g., SPARQL, RDQL, RQL) have been developed with activity. In this situation, usage of storage based on relational database (RDB) with SPARQL that is the most representative query language has a problem. SPARQL cannot search data in RDB model because RDB model use SQL as query language. Therefore, the development of SPARQL-to-SQL translation algorithm is required. Currently, several translation algorithms have been presented. However, the proposed algorithms have the following problems. The algorithms are dependent on a specific storage model and it requires much cost for modification and verification. We already proposed a system model for independent usage upon storage structures of an algorithm. The goal of this paper is to show explicitly its performance efficiency, and thus this paper first defines cost evaluation models and presents the quantitative evaluation results.