In order to obtain an electromagnetic transmission device and an electromagnetic transmission system that emit high-power continuous microwaves stably onto a material or an irradiation target in electromagnetic heating systems and electromagnetic power transmission systems that are required to emit electromagnetic waves such as high-power microwaves, the electromagnetic transmission device, the power amplification device, and the electromagnetic transmission system emit, onto an irradiation target, electromagnetic waves that are modulated by a repeating pulse with a predetermined transmission duty cycle, or electromagnetic waves that are modulated by a repeating pulse with a predetermined transmission duty cycle and are amplified.
