Money supply and velocity of money are important variables that affect inflation and product. Velocity of money is a key concept for economic policy, and itchr('39')s getting more important since it is closely related to behavior of the demand for money. In this regard, Friedman believes that the volatility of money growth is the main factor of velocity of money, which in monetary economics literature is known as Friedman’s monetary volatility hypothesis. The purpose of this study is to explore and explain the fluctuations in the velocity of mony from the perspective of Monetarism. In this regard, using Iran’s economic quarterly data for the period 1988(3)-2015(1) and in the framework of causality test, the Friedman hypothesis based on the impact of volatility of money growth on velocity of money is tested for monetary aggregates (M1 and M2). The model used in this paper is extended VARMA, GARCH-M and the estimated method is quasi maximum likelihood (QML). The results support the Friedman hypothesis for the period under study; in other words, there is a causal relationship from money growth volatility to velocity of money.