货币贬值（又称通货贬值）是货币升值的对称，是指单位货币所含有的价值或所代表的价值的下降，即单位货币价格下降。
Currency depreciation (also known as currency devaluation) is the counterpart of currency appreciation. It refers to a decrease in the value contained in or represented by a unit of currency, that is, a decrease in the price of a unit of currency.
货币贬值在国内引起物价上涨现象。意味着同样数量的货币在国内市场上能够购买到的商品和服务减少。这通常是由于通货膨胀等原因导致物价普遍上涨，货币的购买力被削弱。
在国际经济交往中，货币贬值表现为本国货币与外国货币的兑换比率发生变化，本国货币相对外国货币变得更不值钱。
但由于货币贬值在一定条件下能刺激生产，并且降低本国商品在国外的价格，有利于扩大出口和减少进口，因此第二次世界大战后，许多国家把它作为反经济危机、刺激经济发展的一种手段。然而，把握不好也易发展为经济危机。
从国内角度看，货币贬值在金属货币制度下是指减少本国货币的法定含金属量，降低其对金属的比价，以降低本国货币价值的措施；货币贬值在现代纸币制度下是指流通中的纸币数量超过所需要的货币需求量（即货币膨胀）时，纸币价值下降。
从国际角度看，货币价值表示为与外国货币的兑换能力，它具体反映在汇率的变动上，这时货币贬值就是指一单位本国货币兑换外国货币能力的降低，而本国货币对外汇价的下降。例如，如果100美元原兑换600元人民币，现兑换700元人民币，则人民币贬值了。货币贬值在国内引起物价上涨现象。但由于货币贬值在一定条件下能刺激生产，并且降低本国商品在国外的价格，有利于扩大出口和减少进口，因此第二次世界大战后，许多国家把它作为反经济危机、刺激经济发展的一种手段。
Currency depreciation causes price increases domestically. This means that the same amount of currency can purchase fewer goods and services in the domestic market. This is usually due to factors such as inflation, which lead to a general rise in prices and a reduction in the purchasing power of currency.
In international economic transactions, currency depreciation manifests itself as a change in the exchange rate between a domestic currency and a foreign currency, making the domestic currency less valuable relative to the foreign currency.
However, because currency depreciation can, under certain conditions, stimulate production and reduce the price of domestic goods abroad, thereby promoting exports and reducing imports, many countries have used it since World War II as a means to combat economic crises and stimulate development. However, if mishandled, it can easily lead to an economic crisis.
From a domestic perspective, currency devaluation, under a metallic currency system, refers to reducing the legal metal content of a country’s currency, lowering its price per metal, and thereby reducing the value of the currency. Under a modern paper currency system, currency devaluation refers to a decrease in the value of paper currency when the amount of paper currency in circulation exceeds the required demand for the currency (i.e., monetary inflation).
From an international perspective, the value of a currency is expressed as its convertibility into foreign currency, as reflected in fluctuations in the exchange rate. Currency devaluation, in this context, refers to a decrease in the convertibility of one unit of domestic currency into foreign currency, resulting in a decrease in the domestic currency’s exchange rate against the foreign exchange rate. For example, if 100 US dollars originally exchanged for 600 RMB and now exchanged for 700 RMB, the RMB has depreciated. Currency devaluation can cause domestic prices to rise. However, because currency devaluation can, under certain conditions, stimulate production and reduce the price of domestic goods abroad, it can help expand exports and reduce imports. Therefore, after World War II, many countries used it as a means to combat economic crises and stimulate economic development.