Disclosed are a high-efficiency power amplifier and base station device with respect to high-speed, broadband radio communication method. A broadband power supply circuit includes a linear voltage amplifier to which an input signal is applied, a resistor connected to an output side of the linear voltage amplifier, a switching regulator amplifying the voltage difference between both ends of the resistor to convert the amplified voltage difference into current, and a high frequency amplifier. The high frequency amplifier is designed to exhibit high efficiency at a frequency band where the efficiency of the switching regulator starts to be deteriorated, or at a high frequency band where the operation of the linear amplifier is dominant. In this case, the amplification of low frequency components are performed by the switching regulator, and the amplification of high frequency components are performed by the linear amplifier and the high frequency amplifier.