For a program which handles secret information, it is very important to prevent inappropriate information leak from the program with secret data. Denning proposed a mechanism to certify a security of program by statically analyzing information flow, and Kuninobu proposed a more practical analysis framework including recursive procedure handling, although no implementation has been yet made. In this paper, we propose a method of security analysis implementation, and show a security analysis tool implemented for a procedural language. In this work, we extend Kuninobu?s algorithm by devising various techniques for analysis of practical programs that have recursive calls and global variables. This method is validated by applying our tools to a simple credit car program, and we confirm that validation of program security is very useful.