Axial clearance measuring device

There is provided an axial-measuring device 70 which measures an axial play of a conical roller bearing of a transmission. The transmission supports a wide toothed shaft 4, which is equipped with a gear on the conical roller bearings. The axial clearance measuring device 70 includes a force generating unit 30, which is fixed to the large gear shaft 4 and which generates a force to move the transmission back and forth in the axial direction, a position changing unit 60, which is disposed between the power unit 30 and the transmission and changing the axial position of the transmission by using the force of the power generating unit 30, and an additional drive mechanism 40 which has a free end which receives the force of the power generating unit 30 to amplify the force.