Budget process is one of the most important policy processes in every state, which can be an area for using various interest groups' power, the groups that are involved in bargaining process to gain further resources and profit. These influences are important for their role to hampering growth and creating poverty and inequality in different areas of policy and economy. So, with centralization on different phases of this process, it was attempted in the present work, to explain the interest groups' influences on budgeting in Iran. For this, a descriptive-survey method was used and the data were collected by questionnaire. Moreover, data obtained from the employees of President's Strategic Planning and Control Deputy were selected by random sampling. It was found that, although almost all of budget process phases are appropriate for using the interest groups' power in Iran, but it seems that influences in formulation and approval phases are more appropriate.