We investigated shock waves that developed in a traveling-wave field-effect transistor (TWFET) and determine that waves in a TWFET are dynamically governed by the damped nonlinear hyperbolic equation, which is known to have traveling fronts and shock waves as solutions. This paper describes the conditions for shock wave formation in TWFETs and details several results of numerical and experimental investigations for validation. Two different propagation modes developed on a TWFET because of the coupling between the gate and drain lines. A shock wave is generally supported by the slower mode of the above-mentioned two modes and can reflect the faster mode waves originating ahead. Because the shock wave acts as a moving reflection wall, the carrier frequency of reflected waves increases due to the Doppler effect. This mechanism leads to an effective method of frequency conversion.