阴阳道（日语：阴阳道，おんみょうどう），源于中国阴阳家五行学说，传入日本后，逐渐发展成富有特色的一门自然科学与咒术系统，成为日本神道的一部分，同时也是日本法术的代名词。

史实上的阴阳道，以「天文」「历法」「漏刻」等为正职，而并行「占卜」「追傩」等事。同时身负科学家与方技师的身分。然而在民间传说中，却往往讹传为法术的用户。以安倍晴明『占事略决』的「十二神将」为例，其所指的是中国六壬法中配合「黄道十二宫」十二月将所需的神将，乃是作为占卜推算之用，民间却将之讹传为晴明所使役的十二式神。时至今日，虽因梦枕獏『阴阳师』一书的畅销，而令阴阳道为人所津津乐道，然而民众对阴阳道的正确认知却尚待加强。奉行阴阳道的术师，称之为阴阳师。

Onmyōdō(陰陽道, also In'yōdō, lit. ‘The Way of Yin and Yang’) is a traditional Japanese esoteric cosmology, a mixture of natural science and occultism. It is based on the Chinese philosophies of Wu Xing (five elements) and Yin and yang, introduced into Japan at the beginning of the 6th century. It was accepted as a practical system of divination. These practices were influenced further by Taoism, Buddhism and Shintoism, and evolved into the system of onmyōdō around the late 7th century. Onmyōdō was under the control of the imperial government, and later its courtiers, the Tsuchimikado family until the middle of the 19th century, at which point it became prohibited as superstition.