This study intends to investigate the relationship between change readiness, change competency, and willingness to change of middle management. It also attempts to discuss the effectiveness of micro-learning, the learning method that has recently been actively utilized in many organizations, by providing research subjects with advanced micro-learning sessions and assessing their effect. This study conducted research where 275 mid-level managers of company A, which is in the process of an HR policy overhaul, participated. Following one group training session, they took three micro-learning sessions out of their own volition. Major findings of this study are as follow. First, post-test change readiness diagnosis results did change after the group training, compared to pre-test readiness results as improvements were found in appropriateness and leadership support. However, no statistically significant difference was found in self-efficacy and personal valence. Second, post-test change readiness turned out not to be able to affect willingness to change, and post-test change readiness and willingness to change were completely mediated by change competency. Third, micro-learning participation rates did not have a meaningful mediation effect on the predictability of post-test readiness and change competency on willingness to change. Based on its findings, the study suggests the following strategies. Organizations need to enhance their members’ change readiness and change competency in order to increase their willingness to change. In doing so, departments/teams that are involved in change management should consider learning as a significant determinant for establishing change readiness among employees. In addition, it is deemed to have offered a foundation for future research on micro-learning’s effectiveness, that is yet to be studied in depth. It is hoped that the attempts made in this study would serve as an academic basis for follow-up empirical research on expanding the use of micro-learning.