A folk instrument is a traditional musical instrument that has remained largely restricted to traditional folk music, and is not usually used in the classical music or other elite and formal musical genres of the culture concerned, though related instruments may be.

It can be made from wood, metal or other material; all the major families of instruments are represented. The instruments can be percussion instruments, or different types of flutes or trumpets, or string instruments that are plucked, hammered or use a form of bow.

Some instruments are referred to as folk instruments because they commonly appear in folk music, even though they are also used in other types of music; for example, the classical violin and the folk fiddle are usually identical.