The present invention aims to provide a plasma generator capable of creating a spatially uniform distribution of high-density plasma. This object is achieved by the following construction. Multiple antennas are located on the sidewall of a vacuum chamber, and a RF power source is connected to three or four antennas in parallel via a plate-shaped conductor. The length of the conductor of each antenna is shorter than the quarter wavelength of the induction electromagnetic wave generated within the vacuum chamber. Setting the length of the conductor of the antenna in such a manner prevents the occurrence of a standing wave and thereby maintains the uniformity of the plasma within the vacuum chamber. In addition, the plate-shaped conductor improves the heat-releasing efficiency, which also contributes to the suppression of the impedance.