在理论物理学里，明显对称性破缺（explicit symmetry breaking）是对称性破缺的一种。假若系统的哈密顿量或拉格朗日量本身存在一个或多个违反某种对称性的项目，导致系统的物理行为不具备这种对称性，则称此为明显对称性破缺。这术语特别适用于大致具有对称性、违反对称项目很小的系统。

这类的项目有许多种可能的来源：

明显对称性破缺与自发对称性破缺大不相同，后者的定义方程序满足对称性，但是系统的最低能量态（真空态）打破了这对称性。

In theoretical physics, explicit symmetry breaking is the breaking of a symmetry of a theory by terms in its defining equations of motion (most typically, to the Lagrangian or the Hamiltonian) that do not respect the symmetry. Usually this term is used in situations where these symmetry-breaking terms are small, so that the symmetry is approximately respected by the theory. An example is the spectral line splitting in the Zeeman effect, due to a magnetic interaction perturbation in the Hamiltonian of the atoms involved.