A charged particle irradiation system comprising: a charged particle beam generator that repeats injection of charged particles, acceleration of the charged particles, an extractable state after finishing the acceleration, and deceleration of the charged particles; an irradiation nozzle that irradiates an irradiation object with a charged particle beam supplied from the charged particle beam generator; and a control system that controls the charged particle beam generator and the irradiation nozzle, the control system having: an irradiation object state variation signal reception function of receiving signals from an irradiation object monitoring device that monitors state variation of the irradiation object; an extraction permission state setting function of setting an extraction permission state by outputting an extraction permission signal in sync with the state variation of the irradiation object, characterized in that the control system further has an extraction control function of commanding charged particle beam extraction when the charged particle beam generator is in the extractable state and in the extraction permission state, while commanding stoppage of the charged particle beam extraction when the charged particle beam generator is not in the extraction permission state even if the charged particle beam generator is in the extractable state; and an extractable state maintaining function that operates after the end of the extraction permission state and maintains the extractable state of the charged particle beam generator even after the end of the extraction permission state, wherein the extraction control function commands the charged particle beam extraction again when the extraction permission state starts again during the operation of the extractable state maintaining function, while commanding the deceleration of the charged particle beam generator after the end of the operation of the extractable state maintaining function. a charged particle beam generator that repeats injection of charged particles, acceleration of the charged particles, an extractable state after finishing the acceleration, and deceleration of the charged particles; an irradiation nozzle that irradiates an irradiation object with a charged particle beam supplied from the charged particle beam generator; and a control system that controls the charged particle beam generator and the irradiation nozzle, the control system having: an irradiation object state variation signal reception function of receiving signals from an irradiation object monitoring device that monitors state variation of the irradiation object; an extraction permission state setting function of setting an extraction permission state by outputting an extraction permission signal in sync with the state variation of the irradiation object, characterized in that the control system further has an extraction control function of commanding charged particle beam extraction when the charged particle beam generator is in the extractable state and in the extraction permission state, while commanding stoppage of the charged particle beam extraction when the charged particle beam generator is not in the extraction permission state even if the charged particle beam generator is in the extractable state; and an extractable state maintaining function that operates after the end of the extraction permission state and maintains the extractable state of the charged particle beam generator even after the end of the extraction permission state, wherein an irradiation object state variation signal reception function of receiving signals from an irradiation object monitoring device that monitors state variation of the irradiation object; an extraction permission state setting function of setting an extraction permission state by outputting an extraction permission signal in sync with the state variation of the irradiation object, characterized in that the control system further has an extraction control function of commanding charged particle beam extraction when the charged particle beam generator is in the extractable state and in the extraction permission state, while commanding stoppage of the charged particle beam extraction when the charged particle beam generator is not in the extraction permission state even if the charged particle beam generator is in the extractable state; and an extractable state maintaining function that operates after the end of the extraction permission state and maintains the extractable state of the charged particle beam generator even after the end of the extraction permission state, wherein