To provide an inexpensive torque measuring device of a simple constitution, which measures a torque between a collar of a bearing ring and a large end surface of a tapered roller.

This torque measuring device comprises a shaft 1 integrally engaging with an inner ring 31 of the tapered roller bearing 30 as a torque measuring object, and a housing 2 integrally engaging with an outer ring 32 of the tapered roller bearing 30. A cylindrical body 13 having a collar corresponding part 12 coming into contact with the end surface on the large end side of a tapered roller 33 of the bearing 30 is disposed separately from the inner ring 31. The cylindrical body 13 is supported by the shaft 1 via a rolling ball bearing 14, the rotation with respect to the shaft 1 is restrained by a restraining means 16A, and a drive force measuring means 20A for measuring a drive force acting on the cylindrical body 13 is provided.