The Shurangama or Śūraṅgama mantra is a dhāraṇī or long mantra of Buddhist practice in China, Japan and Korea. Although relatively unknown in modern Tibet, there are several Shurangama Mantra texts in the Tibetan Buddhist canon. It is associated with Tangmi and Shingon Buddhism.
The Mantra was, according to the opening chapter of the Śūraṅgama Sūtra, historically transmitted by Gautama Buddha to Manjusri to protect Ananda before he had become an arhat. It was again spoken by the Buddha before an assembly of monks and lay adherents.
Like the popular six-syllable mantra Om mani padme hum, and the Nīlakaṇṭha Dhāraṇī, the Shurangama mantra is synonymous with practices of Avalokiteśvara, an important bodhisattva in both East Asian Buddhism and Tibetan Buddhism. The Shurangama Mantra also extensively references Buddhist deities such as the bodhisattvas Manjusri, Mahākāla, Sitatapatra Vajrapani and the Five Dhyani Buddhas, especially Bhaisajyaguru. It is often used for protection or purification for meditators and is considered to be part of Shingon Buddhism in Japan.