In this paper a structural monetary base model is developed. An important feature of this approach is that the model combines three parts of the determinants of the monetary base. The three parts are the commercial bank the public and the central bank. Bank behaviour relies on an explicit specification of a maximum profit-seeking and risk-averse model which describes the determinants of the supply of deposits by banks as well as their demands for earning assets and (free) reserves. The behaviours of the public and central bank are set up exogeneously. According to the structural model we derive the monetary base equation which is determined by various financial and real variables endogenously.