以物易物（英语：barter economy）又称物物交换，是有社会契约或明确协议条件下的交换价值模式。与礼物经济自由价值模式相反。用自己已有的物品或服务与别人交换，以换取别人的物品或服务，是一种现有贸易模式出现之前已有的交易方式。早于人类会使用货币作买卖之前，人类已经懂得以物易物。以物换物不同于买卖，并没有使用任何金钱作交易的工具，所以以物易物不一定是一场等价交换。和市场经济一样，以物易物是人类形成等级制度的经济基础，属于等级制度的文化体系，有明显的“经济”体系特性。

Barter is a system of exchange where goods or services are directly exchanged for other goods or services without using a medium of exchange, such as money. It is distinguishable from gift economies in many ways; one of them is that the reciprocal exchange is immediate and not delayed in time. It is usually bilateral, but may be multilateral (i.e., mediated through barter organizations) and, in most developed countries, usually only exists parallel to monetary systems to a very limited extent. Barter, as a replacement for money as the method of exchange, is used in times of monetary crisis, such as when the currency may be either unstable (e.g., hyperinflation or deflationary spiral) or simply unavailable for conducting commerce.