The aim of this study is to explore the influence of job autonomy on employee proactive behaviors and employee deviant behaviors and to investigate the mediating effect of self-efficacy. In this study, data were collected from 169 employees in Taiwan in two waves by questionnaire survey. Time interval is two weeks. We tested the hypothesis by regression analyses and bootstrap. Results showed that (1) job autonomy was positively related to self-efficacy; (2) self-efficacy mediated the positive relationship between job autonomy and proactive behaviors. (3) self-efficacy mediated the negative relationship between job autonomy and deviant behaviors. Practical implications and future suggestions were discussed.