A control part 30 includes: a DRR image creation part 31 that creates a DRR image including a specific site; a specific site projection part 32 that creates a projection region image representing the region of the specific site; a discriminator learning part 33 that learns a discriminator for recognizing the region of the specific site by performing machine learning with use of the DRR image and the projection region image as a training label image; a specific site region detection part 34 that detects the region of the specific site by performing discrimination using the discriminator learned by the discriminator learning part 33 on an X-ray fluoroscopic image including the specific site; and a radiation signal generation part 35 that transmits a treatment beam radiation signal to an irradiation device 90 when the region of the specific site detected by the specific site region detection part 34 is included in the radiation region of a treatment beam.