Background: Daily functioning is an important aspect of chronic pain management, particularly for individuals living with complex regional pain syndrome (CRPS). Previous studies have established that emotional support from significant others is beneficial for chronic pain patients. However, emotional support can be discrepant from one's preference and can also fluctuate. Thus, the present study investigates the role of instability in emotional support discrepancy on the daily functioning of patients with CRPS. Methods: Participants consisted of 21 CRPS patients. Google Forms was used to obtain daily diary ratings over 15 days.The mean square of successive differences was calculated as an indicator of instability of emotional support discrepancy. Statistical analysis was conducted using hierarchical linear modeling. Results: Hierarchical linear modeling reveals that the moderating effect of instability in emotional support discrepancy on the relationship between daily pain severity daily activity avoidance (coefficient=0.01, t (292)=5.57, p＜.001), activity interference (coefficient=0.01, t (292)=5.98, p＜.001), distraction (coefficient=0.01, t (292)=5.10, p= .007) was statistically significant. Conclusions: The results of this study suggest that instability in emotional support discrepancy reduces the buffering effect of emotional support.