Objectives: This study aimed to examine the effect of intrinsic motivation and mother's rational parenting behavior on academic procrastination of middle school students, and to verify the mediated moderation effect of self-control. Methods: The participants of this study includes children ages 13 through 14 years old (N = 267); all of whom attend school in Busan, S. Korea. Collected data were used analyzed by the SPSS 25.0 and PROCESS MACRO (mode l8) by Hayes (2013). Results: The relationship of mother's rational parenting behavior with the academic procrastination level was mediated by self-control. Additionally, intrinsic motivation level moderated the relationship between mother's rational parenting behavior and academic procrastination. Further, level of intrinsic motivation had a mediated moderation effect from mother's rational parenting behavior to the academic procrastination, through the self-control. Conclusion: These results indicate that high level of intrinsic motivation is an important factor in preventing academic procrastination of middle school students.