PURPOSE: To make it possible to improve the sealing property of the titled device by setting a correct angular positional relationship between both seroll members and then determining correct angular positions of all mechanism, when assembling a compressor.

CONSTITUTION: Since the pocket of a movable ring 51 and the pocket of a stationary ring 61 assume a state where the pockets of the rings pinch a ball 200 without any gap therebetween, the ball 200 moves in the driving direction responsive to the rotational movement of the movable ring 51, and further the stationary ring 61 is moved. Accordingly, all the mechanisms of a compressor 1 assume a state at the time of compression. For the last place, a front end plate 70 and a casing are fixed in the stationary hole by means of a bolt, and a locating rod 80 is pulled out. As a result, angular distortions of a crank mechanism, a movable scroll member 40, a stationary scroll member 30, a ball coupling mechanism and the casing, is eliminated, and the sealing property of the device is improved.