交换算符(英语：Exchange Operator)是一种量子力学算符，作用于多粒子量子系统。

交换算符的定义如下：

其中，即为交换算符。其作用为，将系统中两个粒子所处的态交换。在上面的例子中，态变换成为。显然，对同一个系统做两次交换可以得到原系统。假设交换算符的本征值为,则

所以，。由此得到交换算符是自伴算子且是幺正算符。

In quantum mechanics, the exchange operator is a quantum mechanical operator that acts on states in Fock space. The exchange operator acts by switching the labels on any two identical particles described by the joint position quantum state . Since the particles are identical, the notion of exchange symmetry requires that the exchange operator be unitary.