This study aims to examine the mediating effect of internalized shame, moderated by sociality, on the causational relationship between socially prescribed perfectionism and anger-in, anger-out of high school students. A total of 365 high school students responded to the survey. Excluding missing data, 362 data points were analyzed using SPSS 27.0 and PROCESS Macro Model 14. The results of this study are as follows, First, the partial mediation effect of internalized shame on the relationship between socially prescribed perfectionism and anger-in and anger-out was confirmed. Second, the relationship between internalized shame and anger-in was moderated by sociality. Third, the relationship between internalized shame and anger-out was not moderated by sociality. The present study contributes to an integrated understanding of the pathways of socially prescribed perfectionism through internalized shame to anger-in and anger-out by separately elucidating the processes, and suggests the possibility of therapeutic interventions by identifying the moderating effect of sociality.