To simplify a process of suppressing an increase in a reflected wave power caused by IMD, provided is a high-frequency power supply system for providing a high-frequency power to a load, including: a first power supply for supplying a first high-frequency power to the load; a second power supply for supplying a second high-frequency power to the load; and a matching device. The matching device provides a system clock to each of the first power supply and the second power supply. The second power supply outputs a second high-frequency voltage at a control period determined based on the system clock provided from the matching device. The first power supply outputs a first high-frequency voltage obtained by frequency modulation of a fundamental wave signal having a first fundamental frequency and through amplification, in each control period determined based on the system clock provided from the matching device.