"Diary of a Madman" narrates the story of a "madman" in the first person voice. He is afraid of everyone's eyes and always feels that people want to harm him and eat him. The doctor saw him and asked him to "recuperate", and he thought it was to make him fat so that he could eat more meat. He remembered that his eldest brother once told him about "changing children to eat" and "sleeping on skin and eating flesh". Then he remembered that when his "sister" died, his eldest brother advised his mother not to cry, so he thought that the sister was eaten by his eldest brother. The more the "madman" resisted "cannibalism", the more he was considered a "madman". When he was completely disappointed in changing the surrounding environment, he also "cured" and went to be an officer-in-waiting somewhere. The "madman" in the novel is actually an awakened intellectual figure. He is surrounded by people whose souls have been eroded by feudal ethics. What he fears and resists is the feudal tradition of cannibalism.