A stomp box (or stompbox) is a percussion instrument consisting of a small box placed under the foot, which is tapped or stamped on rhythmically to produce a sound similar to that of a bass drum. A stomp box allows a performer such as a singer or guitar player to create a simple rhythmic self-accompaniment. Stompboxes are most commonly^{[according to whom?]} used in American folk and blues music, but they are also used across the musical spectrum.

There are commercially produced stomp boxes available, but performers often simply mount a dynamic microphone inside whatever wooden box they have handy. Some homemade stomp boxes include customized features such as a built-in preamp or equalizer.

In 2010s-era use, a simple piezo transducer (or sometimes a microphone) is located inside the box to allow amplification of the stompbox's bass sound through the PA system or bass amplifier. Other stompboxes such as the PorchBoard Bass and the Peterman acoustic use magnetic sensors designed to produce low-end frequencies.