This study has two objectives, first identifying the level of religiosity and the level of employee's performance, second, analyzing the effect of religiosity on employee's performance. This research is a quantitative research. For the selection of samples, nonprobabilistic sampling technique was used, namely purposive sampling method. Subjects' criteria were Muslim and permanent employees. The population of this research was all employees of a Company located in Central Java. Data obtained through questionnaires distributed to respondents. the questions are adapted from several previous studies and written in 5 Likert scales. Questions are used after passing the validity and reliability test. The data analysis technique for the first purpose was descriptive analysis, while for the second purpose was simple regression analysis. The majority of respondents were 20-30 years old, male, graduate from senior high school, with tenure of less than five years. The results showed that employee's performance can be categorized as high. The highest performance indicator were discipline, work completion, and procedure-based work. The lowest performance indicator was never absence. Religiosity of employees can also be categorized as high. The highest indicator of religiosity is to believe that God exists, to believe in heaven and hell, and to believe that God is watching over. While the lowest indicator of religiosity was always reading the Holy Quran. The results indicate a positive and significant influence of the religiosity on employee's performance. Therefore, to improve employee's performance, it can be achieved by improving their level of religiosity, especially the belief that Allah is supervising.