A large table 30 is rotatably disposed at a position within an area that includes a projected area toward which shot is projected and a non-projected toward which no shot is projected. A plurality of small tables 32 are disposed on the large table 30. Each of the small tables 32 has a rotating shaft 33 that is parallel to the rotating shaft 31 of the large table 30. Thereby each of the small tables 32 can rotate. Workpieces 12 are placed on the small tables 32. A centrifugal projector 20 centrifugally accelerates shot to project it toward the workpieces 12 on the small tables 32. Each of the workpieces 12 on the small tables 32 is pressed down from above by the holding member 48 of the holding mechanism 46. The holding member 48 can rotate along with the workpiece 12.