弦乐器是指以弦振动而发出声音的乐器之总称。

依使弦发声的方法，可分为下列三种：

• 击弦乐器：又称打弦乐器，利用槌击打弦而发声，例如钢琴、翼琴、扬琴等。
• 拨弦乐器：又称弹拨乐器，透过弹、拨弦而发声，例如竖琴、吉他、里拉琴、羽管键琴、古筝、琵琶等。
• 弓弦乐器：又称擦弦乐器，利用弓摩擦弦而发声，例如小提琴、中提琴、大提琴、低音提琴、二胡等。

String instruments, stringed instruments, or chordophones are musical instruments that produce sound from vibrating strings. In most string instruments, the vibrations are transmitted to the body of the instrument, which also vibrates, along with the air inside it. In the Hornbostel-Sachs scheme of musical instrument classification, used in organology, they are called chordophones. Common instruments in the string family include the violin, guitar, sitar, electric bass, viola, cello, harp, double bass, rebab, banjo, mandolin, ukulele, and bouzouki.