To provide a dynamic load-testing device for eliminating the need for incorporating a spindle unit into the machine and exchanging a work and for testing the dynamic load of a rotor extremely easily and economically, and at the same time performing the dynamic load test while a load is being applied for a long time.

In a dynamic load-testing device 1, load-generating devices b1 and b2 and displacement-measuring equipment c1 and c2 are installed on the upper surface of a substrate 8. Then, the displacement-measuring equipment c2 and the load-generating device b1, and then the displacement-measuring equipment c1 and the load-generating device b2 are arranged so that they are vertical to the rotary axis of a test bar (a) that is sealed to a spindle 3 of a spindle head 2, and oppose each other while sandwiching the rotary axis of the test bar (a). Also, the load-generating devices b1 and b2 are connected to a computer (e) via a load controller (d).