The frequency of foreign exchange intervention by the Ministry of Finance of Japan(MOF) has increased dramatically past two years or three. The Bank of Japan acting asagency of MOF has also intervened in the short term money market by itself , from timeto time, to sterilize the yen flooding into it. However, the effectiveness of the operationscould be different from one type of operation from the other because the transactionstaken place between the monetary authorities and the private sectors are completelydifferent. It is why we have employed Asset-Liability-Matrix (ALM) derived from theflow-of-funds accounts to evaluate the effectiveness of each type of operations . Theresults can be summarized as follows. 1) Foreign exchange interventions are effectiveonly when the dollar bought in the operation is invested abroad, that is either in theform of U.S. TBs, T-Notes or making deposit in FRB. 2) Only in some cases , sterilizationor reverse-sterilization cancels out the effects of foreign exchange interventions . Itdepends on the type of the operation BOJ chooses. 3) Some type of non-sterilizing moneymarket operation unintentionally cancels out the effects of foreign exchangeintervention. The conclusion is that the effectiveness of the foreign exchangeinterventions as well as the money market operations largely depends on the type of theoperations, so that it is worthless to examine the effectiveness of the operations withoutgoing into the details.