Usually, the central government is very good at buying and selling foreign exchange in the market, buying foreign exchange with Japanese yen or selling foreign exchange to recover Japanese yen. When it is necessary to control the appreciation of the yen, a large amount of yen is invested in the foreign exchange market to buy foreign exchange, that is, the supply of yen in the foreign exchange market increases and the yen is bearish, which can effectively control the appreciation of the yen. Similarly, when the Japanese yen needs to appreciate, foreign exchange is thrown out to buy Japanese yen, that is, the demand for Japanese yen in the foreign exchange market increases and the supply decreases, which in turn leads to the appreciation of Japanese yen. The relationship between supply and demand of money in the foreign exchange market can determine its rise and fall. Secondly, the central bank can also control the change of the value of the yen through window guidance.