This study analyzes type variations of the ‘stepmother’ and ‘sister’ in the full-length novels of Park Kyong-Ni and attempted to point out their meanings. The pattern of “negative stepmother” that appeared in classical and new novels also appeared repeatedly in Park Kyong-Ni’s full-length novels and this was because a change took place in later full-length novels. Novels analyzed with focus were Jaegwiyeol(1959), Eunha(1960), Kimyakgukeue Ddaldeul(1962), and Nabiwa Unggungkwi(1969). The stepmother that appears in Eunha is a type that appears often in the classic and new novels of Korea. While the stepmother newly gained the role and status of ‘mother’, she forms a competitive relationship with the daughter of the former wife while still refusing to be a member of the family and she puts the former wife’s daughter in critical situations by committing misdeeds. However, the young stepmother in Nabiwa Unggungkwi actually becomes a victim to the malicious and morbid harassment of the former wife’s daughter. This stepmother is a good-natured figure who shows a sense of guilt for failing to fulfill her responsibilities of upbringing and education and she eventually dies as a victim to a bomb during the war, leaving her young biological daughter behind. On one hand, the sisters in Jaegwiyeol and Kimyakgukeue Ddaldeul are not strongly bonded but when one is caught in a crisis, the other one claims to be of help. Unlike this, the sisters in Nabiwa Unggungkwi have a bond that cannot be broken. They are half-sisters that bind each other so severely that they hinder each other’s growth and they eventually end up disintegrating. Through such analyses, it is shown that issues of human nature are dealt with more acutely by breaking the ‘young stepmother’ away from convention by placing her in the position of the victim to amplify the conflicting relationship between sisters, unlike in previous pieces. This study was significant in that it looked into how previously repetitive character type changes appeared in full-length novels in conditions that clearly display the writer’s determination to leave behind a masterpiece.