This research is proposed about decision in eligibility for accepting and rejecting student in vocational school. Prediction is one area in data mining that discuss about classification. One method of algorithm in prediction is Naïve-Byes Decisions Algorithm. Variable will be counted by Naive-Byes Decisions algorithm that content of final exam, report, psychology, interview, and competency. Execution for the first step is transforming each variable into ranging values. Step forward is continued to calculate possibility value for every variable. In 270 student, the research has been resulted the validation test is 199 same as actual condition. Precision is 96,1%, recall is 99,3%. The result is meaning that the algorithm has ability to get the decision in accepting manner with 74,87% accuracy. The value gives the reasoning that has not all submitting students are accepted by the school. Meanwhile, the algorithm has giving fair process for accepting the candidate. The impact of this research is the school can predict how many students is accepted and rejected. So, school will prepare for how many rooms should be available