This study aims to comparatively analyze the factors influencing the rapid changes in human resource management (HRM) practices in Korean firms following the IMF economic crisis from two perspectives: rational choice and institutional isomorphism. For the empirical analysis, hypotheses were established from the rational choice perspective positing that firms' competitive strategies, product market competition, and perceptions of labor market flexibility would have a positive (+) effect on the adoption of innovative HRM practices. From the institutional isomorphism perspective, hypotheses were established positing that proximity to the public sphere, foreign ownership ratio, the status and size of the HR department, foreign degree acquisition as a basis for CEO networks, and chaebol affiliation would have a positive (+) effect on the adoption of innovative HRM practices. The data used for the analysis came from the "Survey on Changes in Management Environment and Human Resource Management after the Economic Crisis" conducted by the Korea Labor Institute in 2000. The results of the group-level effect analysis through F-tests showed that both rational choice and institutional isomorphism pressures had statistically significant effects. When examining the influencing factors individually, among rational choice variables, the perception of labor market flexibility, and among institutional isomorphism factors, foreign ownership ratio and chaebol affiliation consistently had a positive (+) effect on the adoption of innovative HRM practices. Among rational choice variables, the differentiation business strategy was found to have a partially positive (+) effect on the adoption of innovative HRM practices. Furthermore, when innovative HRM practices were divided into skill formation aspects and motivation aspects and the influencing factors for each were examined, changes in HRM practices related to motivation were better explained by both rational choice and institutional isomorphism factors than those related to skill formation. This suggests that HRM changes following the economic crisis were primarily concentrated on the motivation aspect.