A controller of a rotary axis includes: a storage unit that stores data of a braking distance for each rotation number of the rotary axis and provides a current braking distance S3 corresponding to a current rotation number of the rotary axis; and a deceleration command calculating unit that calculates a speed command V2 of the rotary axis on a basis of the remaining movement amount S2 and the current braking distance S3; in which the deceleration command calculating unit maintains the current rotation number of the rotary axis in a case in which a difference S4 between the remaining movement amount S2 and the current braking distance S3 is equal to or greater than a predetermined value, and starts deceleration of the rotary axis in a case in which the difference S4 is less than the predetermined value.