In this paper, Blockchain is mentioned as the next-generation core IT technology. As an immature technology, there are not many practical use cases, but it is expected to be widely applied in various industries such as cryptocurrency, finance, public, etc. to increase efficiency and enable new services that did not exist in the past. Nevertheless, the generalization of blockchain technology is still difficult. In particular, from the viewpoint of personal information protection, GDPR of Europe, etc., is becoming stronger. Considering that the core of the blockchain is the change of information sharing and processing method, it is very important how the blockchain can affect, especially from the viewpoint of privacy, and how the Privacy Act can be applied to the blockchain. However, the discussion on this part also seems to be insufficient. Therefore, in this paper, blockchain By analyzing the implications and implications of technologies and services using them from the perspective of the Privacy Act, we will discuss how the blockchain will be used to prevent leakage of privacy.