Intelligence has an important meaning in the enforcement of police whose major mission is the risk prevention over the national stability and order maintenance. The risk prevention includes the prerequisite about the Intelligence when the major mission of police is said to become the risk prevention. Accordingly, police needs personal data for potential criminals or witnesses for the prevention or precaution of specific risks on individuals. Police has collected and used information necessary for their job performance from the beginning in an effort to promptly and effectively carry out their missions including the public stability and order maintenance, because their job performance is difficult without personal information in taking actions for the risk prevention and criminal investigation. In order words, the collection and processing of personal information on the police investigation can be said to be the core of police enforcement. As the Personal Information Protection Act has been recently established, police handling personal information on the police investigation has to take more specific responsibility for obligations to protect personal information in terms of laws. Anyone who handles personal information should pay more special attention to the prevention and protection of personal information. Although both the investigation activity and the protection of personal information for the national security have a common denominator to deal with information, there are conflicts between public interests and private interests, which also stand for problems on the conflict of rights. It is natural that there should be room for different conclusions depending on the value system or the outlook on the world of a person making a judgment on which value of rights should be prioritized as a principle for solutions when the basic rights are conflicted. In addition, it is necessary to consider the existence of the obligation not to interfere or the limit of the obligation not to interfere with regard to each basic right in solving the conflicts between the basic rights. Also, the specific circumstances relating to the matter in question should be sufficiently considered. Accordingly, this essay suggested plans to protect personal information as well as the efficiency of works on the police investigation, after identifying the status and problems in collecting and processing personal information on the police investigation, while learning the legal grounds and principles relating to the collection and processing of personal information by police.