A control method and apparatus of a circular accelerator can adjust a timing of emitting a charged particle beam in the circular accelerator. Generation of a clock pulse having a fixed period is suspended after acceleration of the charged particle beam has been ended and the generation of the clock pulse is resumed when a beam irradiation request is produced on the basis of a state of an object to be irradiated during the suspension state of generation of the clock pulse. An emitter is operated in accordance with the clock pulse generated again.
