This device for controlling a radiation treatment device is provided with a gantry for supporting a radiation emitting device so as to enable rotation thereof about a first axis, and a ring for supporting the gantry so as to enable rotation thereof about a second axis intersecting with the first axis, the device for controlling a radiation treatment device being provided with a movement path information storage unit for storing movement path information set in the radiation emitting device, and a control unit for providing a limit to the rotation speed of the gantry and the rotation speed of the ring while maintaining the ratio of the rotation speed of the gantry and the rotation speed of the ring indicated by the movement path information, on the basis of the rotation angle of the gantry and the rotation angle of the ring.
