The personal data right is a personal right, not a property right, and the personal data right is mainly in the field of public law. Therefore, personal data right is mainly a constitutional right. In the area of public law, the data subject's right to self-determination is greatly restricted. The public authority may collect and use personal data without the consent of the data subject based on public interest or the necessity of management functions. In order to avoid infringement of the rights of citizens on personal data by public authorities, public authorities must obey the principle of functional necessity and the principle of parties' knowledge when collecting personal data of citizens. When using personal data, they must abide by the specific purpose principle. As a constitutional right, personal data right has the function of preventing public power from violating the personal data rights of citizens. On the other hand, when the right of personal data of citizens is infringed by other civil subjects, he(she) has the right to request the public power to bear the protection. If so, as a constitutional right, the right to personal data is complete and self-contained.