Ruyi Jingu Bang (Chinese: 如意金箍棒; Pinyin: Rúyì Jīngū Bàng, literally meaning "Ideal Golden-bound Cudgel"), or simply as Ruyi Bang or Jingu Bang, is the poetic name of a magical weapon wielded by the Monkey King in the classic Chinese novel Journey to the West. Anthony Yu translated the name for simplicity as "The Compliant Rod".
It is an iron rod whose size changes ruyi 如意 "as-one-wishes," which Sun Wukong obtains from the undersea palace of Ao Guang, the Dragon King of the East Sea. It is immensely heavy (weighing "13,500 jīn")(8,100 kg/17,820 lbs); in modern measurements, it is slightly heavier than 8.5 metric tons.
It also had the power to multiply itself, and fight according to the whim of its master.
When it is not in use, Sun Wukong shrinks it to the size of a sewing needle and keeps it behind his ear. The novel describes it as being made of "black iron" (烏鐵 wūtiě) with two gold bands (Chinese: 金箍 jīngū) round it near the ends. In adaptations, it is often depicted as being either red, black, or silver in color, or as a solid gold or copper staff.
In some forms of the legend Journey to the West, Ao Guang is shown to have believed that the cudgel was worth nothing until Sun Wukong commanded it to shrink and grow.
This staff is depicted in the movie "The Forbidden Kingdom", although it displayed few of its abilities.
There are several weapons that are based on it in various fictions.