This research aimed to investigate factors that affect computer crime protection behavior, based on the protection motivation theory. Personal factors were considered, including: conscientious personality, perceived value of data, prior experience, and environmental factors. In addition, other factors were evaluated, including: subjective norm, security knowledge, and safeguard costs. These factors are mediated by threat appraisal and coping appraisal. The data were collected from 600 personal computer users by use of a questionnaire. Data were analyzed using structural equation modeling. Findings showed that all factors had significant effects on the computer crime protection behavior. In addition, the results showed that security knowledge, one of the environmental factors, had the strongest effects on coping appraisal which subsequently had the strongest impact on protection behavior.