Korean shamanism, also known as musok (Korean: 무속; Hanja: 巫俗), is a religion from Korea. Scholars of religion classify it as a folk religion and sometimes regard it as one facet of a broader Korean vernacular religion distinct from Buddhism, Daoism, and Confucianism. There is no central authority in control of musok, with much diversity of belief and practice evident among practitioners.

A polytheistic religion, musok revolves around deities and ancestral spirits. Central to the tradition are ritual specialists, the majority of them female, called mudang (무당; 巫堂). In English they have sometimes been called "shamans", although the accuracy of this term is debated among anthropologists. The mudang serve as mediators between paying clients and the supernatural world, employing divination to determine the cause of their clients' misfortune. They also perform gut rituals, during which they offer food and drink to the gods and spirits or entertain them with storytelling, song, and dance. Gut may take place in a private home or in a guttang shrine, often located on a mountain. The mudang divide into regional sub-types, the largest being the mansin or kangsin-mu, historically dominant in Korea's northern regions, whose rituals involve them being personally possessed by deities or ancestral spirits. Another type is the sesŭp-mu of eastern and southern regions, whose rituals entail spirit mediumship but not possession.

Elements of the musok tradition may derive from prehistory. During the Joseon period, Confucian elites suppressed the mudang with taxation and legal restrictions, deeming their rites to be improper. From the late 19th century, modernisers – many of whom were Christian – characterised musok as misin (superstition) and supported its suppression. During the Japanese occupation of the early 20th century, nationalistically oriented folklorists began promoting the idea that musok represented Korea's ancient religion and a manifestation of its national culture; an idea later heavily promoted by mudang themselves. In the mid-20th century, persecution of mudang continued in North Korea and through the New Community Movement in South Korea. More positive appraisal of the mudang occurred in South Korea from the late 1970s onward, especially as practitioners were associated with the minjung pro-democracy movement and came to be regarded as a source of Korean cultural identity.

Musok is primarily found in South Korea, where there are around 200,000 mudang, although practitioners are also found abroad. While Korean attitudes to religion have historically been fairly inclusive, allowing for syncretism between musok and Buddhism, the mudang have nevertheless long been marginalised. Disapproval of mudang, often regarded as charlatans, remains widespread in South Korea, especially among Christians. Musok has also influenced some Korean new religions, such as Cheondoism and Jeungsanism.

The anthropologist Chongho Kim noted that defining Korean shamanism was "really problematic". He characterised "Korean shamanism" as a largely "residual" category into which all Korean religious practices that were not Buddhist, Confucian, or Christian were placed. Scholars like Griffin Dix, Kil-sŏng Ch'oe and Don Baker have conversely presented Korean shamanism as just one facet of "Korean folk religion", the latter sometimes called minsok chonggyo in Korean.

Korean shamanism has varyingly been labelled a vernacular religion, a folk religion, a popular religion, and an indigenous religion. It is a non-institutionalized tradition, rather than being an organized religion akin to Buddhism or Christianity. It has no doctrine, nor any overarching hierarchy, and is orally transmitted. It displays considerable regional variation, as well as variation according to the choices of individual practitioners. Over time, the tradition has displayed both continuity and change.

One term commonly used for this tradition is musok ("mu folklore"), coined by the folklorist Yi Nŭnghwa. Although developed during the Japanese colonial period, when it was employed with derogatory connotations, the term has since become popular with the Korean population and with scholars; the Korean studies scholar Antonetta L. Bruno for instance capitalised it as Musok to serve as a name for the religion. Alternative terms include mugyo, muijŭm, and mu. Mugyo was a neologism introduced in the 1970s by a Protestant theologian Yu Tong-sik.^{[page needed]} In Korea, the term misin ("superstition") is sometimes used for this religion, but is also applied to other religious and cultural practices like geomancy. While misin carries negative connotations in Korean culture, some mudang use it to describe what they do.

Since the late 19th century, English language studies have referred to the mudang as "shamans" and their practices as "Korean shamanism", a label rendered into Korean as shyamŏnijŭm. Introduced to English from the Tungusic languages at the end of the 17th century, the term "shamanism" has never received a commonly agreed definition and has been used in at least four distinct ways. A common definition uses "shamanism" to describe traditions involving visionary flights to perform rituals in a spirit realm, a practice not found in Korean traditional religion. Many scholars avoid the term "shaman" as a cross-cultural category altogether. Its application to Korean religion is controversial, with Chongho Kim deeming it "often unhelpful". The scholar Suk-Jay Yim proposed mu-ism as a more appropriate label than "Korean shamanism", while Dix thought "spirit mediumship" more suitable than "shamanism".