In the case where radiological imaging of a subject to be injected with a contrast agent is performed continuously and a radiation exposure dose of the subject due to the continuous radiological imaging is obtained based on a radiation image signal of each frame detected by a radiation image detector through the continuous radiological imaging, identifying a frame which includes an image signal representing an image of the contrast agent as a contrast agent frame from the radiation image signal of each frame, and correcting the radiation exposure dose based on information of the contrast agent frame and obtaining a radiation exposure dose of the subject for the radiological imaging of the contrast agent frame.
