A wireless transmission device includes an input terminal, control terminals, an amplifying circuit, a matching circuit, and an output terminal coupled to the output of the matching circuit. The amplifying circuit includes unit amplifiers and capacitive elements. Each unit amplifier includes a sub-input terminal, a sub-control terminal, and a sub-output terminal. The sub-input terminal is coupled to the input terminal, the sub-control terminal is coupled to the corresponding control terminal in the control terminals, and the sub-output terminal is coupled to the input of the matching circuit through the corresponding capacitive element in the capacitive elements in series. Each unit amplifier includes a tri-state-type class-D amplifier. The sub-output terminal of each unit amplifier is set to a low level state, a high level state, or a high impedance state based on a control signal supplied to the sub-control terminal or an input signal supplied to the sub-input terminal.