Fidelity is to keep conscience rather than appointments, rules and applicable laws. There is basic difference between keeping conscience and keeping appointments, rules and applicable laws. There may be some wrong appointments, non-righteous rules and bad laws. Conscience is the voice of inner self asking to do the right thing or criticize misbehaviors. Therefore, we feel ashamed when we behave against our conscience. The reason why we cannot keep fidelity and integrity is because of social trend emphasizing competition and satisfaction for desire. In the trend emphasizing competition, it is more important to keep the prescribed rules than keeping conscience. It may make the situation that people will keep the prescribed rules only and don`t mind doing misbehaviors. Moreover, when the competition becomes too fierce, they will be only interested in winning even by doing unrighteous things. What was worse is that people might have cruel mind to get rid of competitors. The fundamental solution for overheated competition and satisfaction for desire is to recover conscience. To behave as conscience command, we need to get rid of unrighteous greed and fill it with original mind. To follow conscience is the fidelity and to behave according to conscience is the integrity. Fidelity and integrity are expressed loyalty to parents, affection to children, brotherly affection between siblings, and fidelity between husband and wife at home. They are expressed as trust between friends in social life and social justice between boss and juniors at work. Fidelity and integrity for the nation can be found in fidelity and loyalty of subjects to their king, and fidelity and loyalty to the nation as public servants. To practice fidelity and integrity, we need to nurture conscience, coerce greed and try not to have unrighteous greed. To nurture conscience, we need to expand Sadan(四端), or perform Geukgibokrye(克己復禮) to remove unrighteous greed by suppressing greed itself. Additionally, we can Gyeokmulchiji(格物致知) by observing natures of other people than mine and inferring our own nature. As we can live a life according to the given nature when we keep fidelity and integrity, we can live the happiest and the most valuable life. As we can have trust between people, we can have effects of the improvement of righteous social ethos.