Purpose: The purpose of this study was to identify the factors influencing file-up family stress in the family with a family member having a chronic mental illness. Method: Data was collected by questionnaires from 365 families with a member having a chronic mental illness, in an outpatient clinic of a General Hospital and Government Psychiatric Hospital in Seoul. The data was analyzed using descriptive statistics, pearson correlation coefficients, and stepwise multiple regression. Result: The score of file-up stress showed a significantly negative correlation with the score of level of hardiness (r=-.31, p=.00), family support (r=-.13, p=.00), family cohesion (r=-.25, p=.00), and sense of coherence (r=-.26, p=.00). The most powerful predictor of file-up stress was family hardiness and the variance was 11.1%. Acombination of hardiness, family support, and sense of coherence account for 14.8 % of the variance in file-up stress of the family with a member having a chronic mental illness. Conclusion: This study suggests that family support, hardiness, cohesion, and sense of coherence are significant influencing factors on file-up stress in the family with a member having a chronic mental illness.