PROBLEM TO BE SOLVED: To suppress worsening of uniformity in a dose distribution even if an error in exposure position of a charged particle beam occurs.SOLUTION: A charged particle radiotherapy device 1 that uses a scanning method to expose a tumor 14 to a charged particle beam B comprises: an exposure unit 2 that exposes the tumor 14 to the charged particle beam B in accordance with a scanning pattern and a control unit 7 that controls the exposure unit 2 on the basis of the scanning pattern. When the exposure unit 2 executes at least two exposures within the same layer set to the tumor 14, the control unit 7 controls the exposure unit 2 on the basis of the scanning pattern displaced per exposure.
