Purpose: To determine associations of illness symptoms, perception of illness, coping with quality of life (QOL) of thyroid cancer patients and identify factors affecting their QOL. Methods: A cross-sectional study was performed using a self-administered questionnaire for 111 thyroid cancer patients after thyroidectomy. They were recruited from the outpatient clinic of one university hospital. Data collection was conducted from August 2018 to November 2018. Results: The QOL was significantly associated with interpersonal coping (β=0.31, p<.001), monthly household income (β=0.30, p<.001), illness symptoms (β=-0.22, p=.017), perception of illness (β=-0.20, p=.031), and education (β=0.18, p=.037) in stepwise multiple regression. These factors explained 33.1% of QOL of thyroid cancer patients. Conclusion: Interpersonal coping is a major contributing factor to QOL. Therefore, thyroid cancer patients need good interpersonal coping for better quality of life.