South Korea has suffered from unprecedented crisis of public power. Illegal and violent ‘assembly and demonstration’ has been prevalent throughout the country on account of shortage of strict countermeasures. The Korean police public power has been swayed by this kind of illegal and violent ‘assembly and demonstration’. What makes matters worse, the police is facing unprecedented crisis by dint of mild and negative exercise of the police public power in so-called ‘Hanwha Group chairman case’ in which Hanwha Group chairman Kim Seung-youn punched bar workers after his son was hurt. Accordingly, this article tried to solve the crisis of the police public power through diagnosing and analyzing the causes of the crisis of the police public power in the aspect of illegal and violent ‘assembly and demonstration’ and so-called ‘Hanwha Group chairman case’. For this aim, this article is composed of 6 chapters. Chapter 1 is on introduction of this essay. Chapter 2 is on the cases of recent crisis of the police public power which is based on illegal ‘assembly and demonstration’ and recent situation of ‘assembly and demonstration’. Chapter 3 covers so-called ‘Hanwha Group chairman case’ which is related to crisis of the police public power. Chapter 4 scrutinizes causes of crisis of the police public power. Chapter 5 scrutinizes countermeasures to cope with crisis of the police public power. In last chapter we can derive conclusions from this study as follows. Freedom of legal and peaceful ‘assembly and demonstration’ shall be guaranteed to the full. But illegal and violent ‘assembly and demonstration’ shall be abstained powerfully and strictly in the name of rule of law. What is more important is establishment of ethics of public office as the policeman. Only establishment of ethics of public office will be the shortcut to reasserting authority of the police public power.