Chronic pain coexists with disability, anxiety, depression, and sleep disturbances, which are factors of pain chronicity in the fear-avoidance model. Self-efficacy for managing pain plays a protective role against pain chronicity. For chronic pain sufferers, social support from caregivers is important. However, such caregivers face enormous physical and mental burdens. This study aimed to assess how self-efficacy and factors related to the fear-avoidance model affect caregiver burden. Participants were 135 chronic pain patients and their caregivers who visited our outpatient pain special clinic. In clinical assessments, numeric rating scale (NRS), pain catastrophizing scale (PCS), hospital anxiety and depression scale (HADS), Athens insomnia scale (AIS), pain disability assessment scale (PDAS), pain self-efficacy questionnaire (PSEQ) for the patients and Zarit Burden Interview (ZBI) for their caregivers were evaluated. Participants were divided into 2 groups (L group ZBI < 24 points and H group ZBI ≥ 24 points) and compared. Regression analyses were conducted to identify factors correlated with the ZBI scores. Compared to L group, H group showed significantly higher NRS and HADs depression scores, and lower PSEQ scores. In univariate regression analysis, ZBI scores were significantly correlated with NRS, PCS, HADS anxiety, HADS depression, PDAS and PSEQ. Multiple linear regression analysis revealed that ZBI scores were significantly correlated with PSEQ. The caregivers who perceived high caregiver burden had significantly higher patients' pain intensity, depression, and lower self-efficacy than those who perceived low caregiver burden. Caregiver burden correlated with the pain intensity, pain catastrophizing, anxiety, depression, disability, and self-efficacy of chronic pain patients. Among these factors, self-efficacy was the most negatively correlated with caregiver burden. Treatments focused on increasing self-efficacy for managing pain have the potential to reduce caregiver burden.