The purpose of this study was to determine the service quality satisfier and dissatisfier factors of family restaurants in Korea by using a qualitative research method, the critical incident technique(CIT). The CIT helps researchers find new factors or attributes by grouping key issues and categorizing common factors from the raw data, critical incidents which critically satisfied or dissatisfied customers. The respondents must describe the incidents in details. There are many previous studies on the attributes related to service qualities, selections, and revisiting intentions and the relationships between the attributes. These studies offer many insights for general trends and directions for managing service qualities, but not how to improve service quality practically. It is difficult to know specific service quality factors especially influencing Korean customers because the factors come from previous research and not from the respondents themselves. Therefore, this research categorized key satisfier and dissatisfier factors from 402 critical incidents described by 261 respondents into 5 groups and 33 subcategories. Real cases and examples are also explained that either critically satisfied for dissatisfied customers at family restaurants.