Abstract: An object of the invention is to provide the orbit control device for modulating the orbital deviations of the charged particle beam and its control method, wherein in the synchrotron making use of induction cells, the charged particle beam orbit control device is comprised of the digital signal processor for controlling the generation timing of an induced voltage in response to the beam position signal from the beam position monitor for sensing the deviations of the charged particle beam on the design orbit of the synchrotron from the design orbit and to the passage signal from the bunch monitor for sensing the passage of the bunch and the pattern generator for generating a gate signal pattern for on/off-selecting the switching electric power supply a according to the master gate signal generated by the digital signal processor.