The sanshin (三線; lit. 'three strings', Okinawan: sanshin) is a Ryukyuan musical instrument and precursor of Japanese shamisen (三味線). Often likened to a banjo, it consists of a snakeskin-covered body, neck and three strings.

The sanshin is believed to have originated from the Chinese instrument known as the sanxian, which was introduced to Okinawa through trade in the 15th century. Over time, the sanshin underwent unique modifications and developments in Okinawa and the Amami Islands, evolving into a distinct instrument. In the 16th century, the sanshin reached Japan, specifically the trading port of Sakai in Osaka. The sanshin was transformed into the shamisen in Japan, which spread throughout the country. As it reached various regions, the shamisen continued to be altered, resulting in variations such as the Tsugaru shamisen and Yanagawa shamisen. Among these, the gottan from Kyushu, retained many characteristics of the sanshin, distinguishing it from other derivatives such as the shamisen.

Played by youth as young as 2, to older people aged 100 or more, there is a sanshin in most Okinawan homes. It is the center of small informal family gatherings, weddings, birthdays, other celebrations, community parties, festivals.

The sanshin is held in great respect among the Ryukyuan culture, and is often viewed as an instrument that carries the voice of the deities, and is regarded as a deity itself. This is reflected in the traditional construction of the sanshin. Sanshin are generally designed to last more than a lifetime, as they are often passed down through the generations of a family.

A traditional Okinawan story, the tale of the 'Husband and Wife Sanshin', tells of a pair of sanshin made from the same core of Okinawan Ebony tree. They were owned by a husband and wife prior to World War II. At the onset of the war, the husband was forced into military service by the Japanese, and therefore had to leave his wife and home. Due to the destruction to main island during the war, the pair of sanshin were in danger, and the war wiped out almost half of the native population.

In an attempt to preserve his and his wife's sanshin, the husband wrapped them up, put them into a wooden box, and buried them deep in the Okinawan forest. Later, they were dug up, and brought back to their rightful home, having made it safely through the violent war. They are currently preserved by the son of the couple.

Traditionally, the sanshin was covered with the skin of the Burmese python, but today, due to CITES regulations, the skin of the reticulated python is also used. Python skin is used for the skin of the body of the instrument, in contrast to the cat or dogskin used traditionally on the shamisen. Though Okinawa is famous for the venomous habu viper, the habu is in fact too small for its skin to be used to make sanshin, and it is believed that the snakeskin for the sanshin has always been imported from Southeast Asia.

Though the pythons used to make sanshin skins today are not an endangered species, the difficulty of distinguishing faux snakeskin from real snakeskin makes transporting real-snakeskin (hongawa) sanshin internationally somewhat risky. Due to international wildlife protection treaties, it is not legal to export snakeskin-covered sanshin to some countries, such as the United Kingdom and the United States. There is some room for interpretation of this, in that the treaties specify that the restriction is for endangered snake species.