The purpose of this study was to examine the junior high school students' knowledge, attitude, self-efficacy, and behavioral intention toward first aid; moreover, to explore the related factors. Through muti-stage sampling, the population was selected from a basal group of 17,200 students in Keelung City. A self-administered questionnaire was used as the investigation instrument. Data of 479 valid samples were collected. The major findings of this study are as follows: 1. The subjects' first aid knowledge was about half. The subjects who were in higher grade and had higher academic achievement as well as first aid learning experience had better first aid knowledge. 2. The subjects' attitude toward first aid was positive. The subjects who were in the seventh grade and had first aid learning experience, first aid experience and certificate as well as more access to first aid information had higher positive attitude toward first aid. 3. The subjects' first aid self-efficacy is somewhat low. The subjects who were the male students and had first aid learning experience, first aid experience, first aid certificate, more access to first aid information as well as taking part in first aid organizations, had higher confidence in first aid. 4. As far as behavioral intention toward first aid was concerned, if the victim was a family member, the subjects would have the highest intention to perform first aid; if a stranger, the lowest. The subjects who were in higher grade and had higher academic achievement, first aid learning experience, first aid experience as well as more access to first aid information had higher behavioral intention. 5. The subjects' first aid knowledge, attitude, self-efficacy and first aid behavior intention were significantly positively related. Demographic variables, first aid knowledge and attitude as well as self-efficacy could explain 34.7% variation of behavioral intention toward first aid. Moreover, first aid attitude, self-efficacy, first aid learning experience and academic achievement were the most important predictors. This research proposed recommendations for first aid education policy as well as guidelines for improvement and enhance the subjects' first aid self-efficacy and the behavioral intention to deal with unintentional injuries.