This thesis is an attempt to examine the past of infectious diseases here, living in the era of covid-19 Pandemic. To this end, I looked at the records of infectious diseases left in Heumyoung, Yu Man-ju's diary. Among them, from March to June 1786, when the measles epidemic in Seoul, Yu Man-ju and his surrounding people's disease-related experiences were reviewed. Measles, which was very popular at the time, was great enough to take the life of the eldest son of King Jeongjo. At this time, Yu Man-ju made every effort to protect his family, especially his younger brothers and children, and in the process, he mobilized his medical knowledge and moved to meet professional medical personnel. As a result, he succeeds in protecting his family from measles. In addition, Yu Jun-ju and Yu San-ju, wealthy relatives of Yu Man-ju, also protected their families from infectious diseases based on their knowledge and economic power. On the other hand, the situation of those who were in economically vulnerable situation was different. Yu Man-ju's cousin Kim I-jung was living in extreme poverty in the outskirts of Seoul. When the infectious disease spread, he was worried because he did not have the economic power to receive medical treatment. The man who had been living in the house of Yu Man-ju was infected and died shortly after the outbreak of measles. His case clearly shows that even though they live in the same house, they suffer from infectious diseases differently depending on their status and economic power, and that the socially weak are more vulnerable to infectious diseases. The records in this diary show that even if they encounter the same infectious disease, the pain and damage suffered by it differ according to the socio-economic status of those suffering the disease. And this pattern overlaps with the present, living in the era of infectious diseases. However, in 1786, King Jeongjo's efforts to protect the people from infectious diseases and the end of the infectious diseases as a result of them give us hope as well. Jeongjo repressed the grief of losing his successor due to measles, encouraged the active operation of the national medical system, firmly rejected the profane discourse about punishing medical professionals who failed to treat the crown prince, and encouraged the state medical staff to focus on the treatment of the infected people. Eventually, on June 29, 1786, the Jeongjo's government declared an end to measles.