It is an objective of the present invention to provide a method capable of protecting personal information.A method for protecting personal information that can be obtained by analyzing a biological sample is provided, wherein the method comprises adding to the biological sample a component obstructing the analysis of another component that provides personal information to be protected. Thus, the analysis of personal information such as genomic information without the person's consent can be technically prevented.In addition, the present invention provides a technique for not only simply protecting personal information, but also for analyzing the once protected personal information as needed.