A lot of privacy related cases, such as information leakage and phishing scam, have been reported in recent years. In such a situation, the Act on the Protechtion of Personal Information was enacted in 2005. In 2015, all residents of Japan received a "MyNumber" card on which is printed their individual numbers. Thus, privacy related techniques are the one of most important issues. The classical techniques, such as encryption algorithm, digital signature, are effective to protect privacy related information from malicious third parties, but, not effective against legitimate users, who may cause privacy related cases. In this paper, we introduces some privacy related issues/techniques, especially, our proposed model named "Privacy Protection Model."