米ドル指数（DXY）は主要6通貨に対するドルの相対価値を示す重要な指標です。短期の変動と長期のトレンドを合わせて確認し、ドルの流れを把握しましょう。
現在の水準、ドルの強さ、世界への影響度をまとめます。
米ドル指数（DXY）は主要6通貨に対する米ドルの相対的な価値を測る指標です。ドルの強弱を判断する基準となります。
The U.S. Dollar Index (DXY) measures the value of the dollar against a basket of six major currencies. The euro carries the largest weight at roughly 57.6%, followed by the Japanese yen, British pound, Canadian dollar, Swedish krona, and Swiss franc. The index was set to a base value of 100 in March 1973 and is calculated in real time on the ICE futures exchange. A rising index means the dollar is strengthening against the basket, and a falling index means it is weakening.
The index is driven largely by interest rate differentials between the U.S. and other economies, relative growth performance, and global risk appetite. The dollar tends to strengthen when the Fed raises rates or the U.S. economy outperforms, and it often gains in crises as investors seek safe-haven currency exposure. Because the euro makes up over half the basket, the index largely mirrors the inverse of the EUR/USD exchange rate. Note that emerging-market currencies are absent from the basket, so DXY can diverge from broader trade-weighted measures of the dollar.
A strong dollar tends to pressure dollar-denominated commodities and gold, and it can trigger capital outflows and heavier dollar-debt burdens for emerging markets. It also weighs on the reported earnings of U.S. multinationals by shrinking the dollar value of overseas revenue. Conversely, a weakening dollar is often read as supportive for commodities, emerging-market assets, and risk appetite broadly. Watching Treasury yields, Fed policy expectations, and eurozone data alongside DXY helps anticipate the dollar's direction.