A data acquisition unit (11) acquires first raw data about an object at a first position and second raw data about the object at a second position. a processing unit (12) evaluates an amount of motion of the object between an acquisition time of the first raw data and an acquisition time of the second raw data. The processing unit (12) calculates a derivative of first plane integrals on a test plane including the first position and the second position by using the first raw data, calculates a derivative of second plane integrals on the test plane by using the second raw data, and evaluates the amount of motion by using a difference between the derivate of the first plane integrals and the derivate of the second plane integrals.