Organization needs a structured and well planned budgeting system to maintain, control and improve it’s operational. Budgetary participation is a budgeting planning process which actively involved peoples impacted by it. Budgetary particpation has negative effect, known as budgetary slack. Budgetary slack is a difference between value attainment and best estimation of budget which forecasted. The result correlation between participatory budget and budgetary slack is not consistent. Without a consistent approach those difference couldn’t be solved. Pemoderation variables which used in this Study to know a correlation between participatory budget and budgetary slack are role ambiguity and budget emphasis as moderating variable. Data collected using questionnaire which distributed to 115 leaders and chief financial officer of SKPD involved in participatory budget System in Kabupaten Belitung Timur. Samples choosen using purposive sampling method. Analytical method in The Study are simple regression anaysis and moderated regression analysis. Result of this study is participative budget has positive impact on budgetary slack. Although, role ambiguity and budget emphasis as moderating variabel can’t impact the correlation.