A digital amplitude modulation device includes power amplifiers, a compositor, a filter, a measurement unit, a protection unit, and a controller. The power amplifiers are arranged in parallel and amplify an input signal in accordance with ON control and stop output in accordance with OFF control. The filter suppresses an unnecessary component to generate an AM signal. The measurement unit measures a measurement value between the filter and a signal output terminal and output the AM signal generated by the filter. The protection unit includes a calculator and a first processing unit. The calculator is formed from an analog circuit and calculates an evaluation value based on the measurement value. The first processing unit is formed from an analog circuit and generates a first control signal by referring to the evaluation value. Upon receiving the first control signal, the controller OFF-controls the power amplifiers.