This research was conducted at PT Kereta Api Indonesia Daop 4 Semarang, a company engaged in the field of transportation services and community services. so it is important for companies to motivate employees to work, so that employees can improve their performance. the purpose of this research is to find out the influence of work motivation on employee performance, and how much that influence. the research sample where 42 employees of PT Kereta Api Indonesia Daop 4 Semarang as respondents. the independent variable of this research was motivation and the dependent variable was employee performance. the method of analysis in this research used validity test, reliability test, simple linear regression test, t test, and the coefficient of determination. and the method of collecting data are questionnaire and literature study. The results of simple linear regression analysis showed that at the Y = 8,235 + 8.12X + e , Regression Equations Multiple linear over a variable ( X ) motivation to work positively influences the variable ( Y ) As for the significant positive impact that the value t work motivation variable ( X ) is amounted to 9.498 with a significance level of 0.000 . Because t count> t table = 9,498 > 2,021 and a significance level of 0.00 < 0.05 then Ho is rejected and Ha accepted. Thus , work motivation has a positive and significant impact on employee performance partially 0.000. And Adjusted R - Square value of 0.685 which indicates that motivation influence on the performance of employees is 68.5 % and the remaining 31.5 % is influenced by other variables that are not described in this study.