Volunteer Computing (VC) is one of methods of distributed computing. In VC process, several volunteers provide their computing resources for some computational purposes. Because most VC is supposed to be executed based on a situation that each volunteer is an honest one, in a case that some malicious volunteers are inside the VC network, the VC contains potential risk of causing to output an unreliable computational result. To improve the reliability of the computational result, several existing VCs adopt a method of majority voting using reliability parameters. However, this method contains potential vulnerability against to “Sybil Attack”. Therefore, in this paper, we propose our VC system using blockchain technology named “Hierarchy-System” to solve these problems and also show the evaluation result executed on a VC system simulated our proposed method.