The nunchaku () (Japanese: ヌンチャク, sometimes "dual-section stick", "nunchuks" (), "nunchucks", "chainsticks", or "chuka sticks" in English,) is a traditional Chinese weapon consisting of two sticks (traditionally made of wood), connected to each other at their ends by a short metal chain or a rope. It is approximately 30 cm (12") (sticks) and 1 inch (rope). A person who has practiced using this weapon is referred to in Japanese as nunchakuka.

The nunchaku is most widely used in martial arts such as Okinawan kobudō and karate. It is intended to be used as a training weapon, since practicing with it enables the development of quick hand movements and improves posture. Modern nunchaku may be made of metal, plastic or fiberglass instead of the traditional wood. Toy versions and replicas not intended to be used as weapons may be made of polystyrene foam or plastic. Possession of this weapon is illegal in some countries, except for use in professional martial arts schools.

The origin of the nunchaku is China; a traditional explanation holds that it was originally used by Chinese farmers as a flail for threshing rice. Another weapon, called the tabak-toyok, native to the northern Philippines, is constructed very similarly, suggesting that it and the nunchaku descended from the same instrument.

In modern times, the nunchaku (Tabak-Toyok) was popularized by the actor and martial artist Bruce Lee and by Dan Inosanto. Lee famously used nunchaku in several scenes in the 1972 film Fist of Fury. When Tadashi Yamashita worked with Bruce Lee on the 1973 film Enter the Dragon, he enabled Lee to further explore the use of the nunchaku and other kobudo disciplines. The nunchaku is also the signature weapon of the cartoon character Michelangelo in the Teenage Mutant Ninja Turtles franchise.

In addition the nunchaku is used in certain contact sports.