The ''zhu'' was a percussion instrument used in the court ritual music of ancient China. It consisted of a wooden box that tapered from the top to the bottom, and was played by grasping a vertical wooden stick and striking it on the bottom face. The instrument was used to mark the beginning of music in the ancient ritual music of China, called ''yayue''. The instrument is rarely used today, with specimens appearing mainly in Chinese museums, although in Taiwan it is still used in Confucian ritual music by the Taiwan Confucian Temple.
The ''zhu'' is mentioned, along with another percussion instrument called ''yu'' , in pre-Qin Dynasty annals, and appears in the ''Classic of History''.
The Korean '''' , a musical instrument that is essentially identical to the ''zhu'', from which it was derived, continues to be used in Korean Confucian court ritual music.