The object of the invention is a method for defining elastic deformations and integral angle between of the most important parts of a gyratory compactor, in which method the angle of gyration of a gyratory compactor is measured during the use of the gyratory compactor. The object of the invention is also a device in accordance with the claim 1, which device includes measuring elements (13, 20, 27, 28) for measuring the angle of gyration of a gyratory compactor. Characteristic to the method in accordance with the invention is the fact that a loading device (1) is adjusted in the place of mass specimen, the loading of which on the gyratory compactor is earlier known and that the gyratory compactor will be in use while the loading device (1) is inside the gyratory compactor. Characteristic to the device in accordance with the invention is the fact that the device includes at least one loading device which can be placed inside the specimen cylinder mold of the gyratory compactor.