To provide a barrel case for a barrel polishing machine without generating a rattling sound in polishing, capable of easily and quickly attaching and detaching a barrel.

A slider 36 movable in the radial direction to the rotational axis of this barrel case 30, is arranged in the barrel case 30 capable of placing the barrel 50, and a clamp claw 37 and a guide pin 38 are also arranged in the slider 36, and meanwhile, a guide board 40 having an oblong hole for inserting the guide pin 38 is rotatably arranged on the guide pin 38. A reinforcing ring 46 for supporting the barrel 50 is arranged in the barrel case 30. When placing the barrel 50, a step part 51a of the barrel is supported by the reinforcing ring 46. Next, when rotating the guide board 40, the guide pin 38 and the slider 36 move in the radial direction along the oblong hole, and the clamp claw 37 is locked on a locking part 51b of the barrel 50, and surely fixes the barrel 50.