To provide a device for forming an orthogonal plane with respect to an axle of an automobile or a vehicle equipping with wheels.

Nuts 3, 3 are screwed into two hub bolts 2, 2 projecting from a wheel 1 of an automobile. A base plate 5 is mounted to the both nuts 3, 3 with mounting bolts 4, 4, and a disc 6 is oscillatably held to the base plate 5. Three adjustment bolts 7, 7 are disposed at an equal position in the circumference direction over the base plate 5 and the disc 6. The distance between the base plate 5 and the disc 6 can be brought in line in the circumference direction by adjusting the amount of screwing of three adjustment bolts 7, 7 respectively. The disc 6 with respect to an axle can be all vertically maintained in the circumference direction. Accordingly, the orthogonal plane with respect to the axle can be extremely simply and more precisely formed.