Abstract
Blockchain is expected to be applied in many fields. However, there are still few cases of implementation. In this paper, I considered why blockchain is not widespread. I considered the strengths and weaknesses of blockchain from the features of hash functions. Blockchain is said to have excellent integrity and availability, but what are its weaknesses? I considered whether the integrity and availability of the blockchain were at a satisfactory level when viewed as a business system. Finally, I described why business owners are reluctant to implement blockchain. Interest in the blockchain itself is high, but it is considered difficult to use as a business system.
