This paper employs monthly data over the 1996-2006 periods to investigate whether currency depreciation in Indonesia has resulted in currency substitution away from Rupiah. To take account of currency substitution, the demand for money that includes the exchange rate in addition to income, interest rate, also an interaction dummy variable between time dummy and exchange rate. The methodology is based on an application of the Johansen and Juselius(1990)cointegration technique. There is no evidence of currency substitution in real M1 equation.