Concurrency and synchronization problems are often caused by database applications concurrently accessing databases managed by DBMS. Most commercial DBMSs support isolation levels to resolve these problems. Verification of isolation levels are most important because consistency and integrity constraints of the database can be violated according to isolation levels of transactions that consists of database applications. We propose a test tool set to verify and reveal faulty settings of isolation levels and implement a prototype of the test tool set. The proposed tool set analyzes the SQL statements of ESQL/C programs, attaches the test codes to verify isolation levels, runs the test transactions and detects errors.