理论物理中，相对于薛丁格方程序之于非相对论量子力学，狄拉克方程序是相对论量子力学的一项描述自旋-½粒子的波函数方程序，由英国物理学家保罗·狄拉克于1928年创建，不带矛盾地同时遵守了狭义相对论与量子力学两者的原理，实则为薛定谔方程的洛伦兹协变式。这条方程预言了反粒子的存在，随后1932年由卡尔·安德森发现了正电子(positron)而证实。

带有自旋-½的自由粒子的狄拉克方程序的形式如下：

其中是自旋-½粒子的质量，与分别是空间和时间的座标。

In particle physics, the Dirac equation is a relativistic wave equation derived by British physicist Paul Dirac in 1928. In its free form, or including electromagnetic interactions, it describes all spin-⁄₂ massive particles such as electrons and quarks, for which parity is a symmetry, and is consistent with both the principles of quantum mechanics and the theory of special relativity, and was the first theory to account fully for special relativity in the context of quantum mechanics. It accounted for the fine details of the hydrogen spectrum in a completely rigorous way.