The plasma generating apparatus includes: an antenna chamber which is disposed adjacently to a plasma chamber that produces a plasma, and which is exhausted to vacuum; an antenna which is disposed in the antenna chamber, and which radiates a high-frequency wave; a partition plate which is made of an insulator, which separates the plasma chamber from the antenna chamber to block a gas from entering the antenna chamber, and which allows the high-frequency wave radiated from the antenna to pass through the partition plate; and a magnet device which is disposed outside the plasma chamber, and which generates a magnetic field for causing electron cyclotron resonance in the plasma chamber.