It is a challenge to make it possible to produce a resonance suppression effect, and perform a stable control even in a case where a spring rigidity of a shaft significantly varies. The challenge is achieved as follows. In an engine bench system in which an engine 1 to be tested and a dynamometer 2 are coupled together by a coupling shaft 3, and a shaft torque control of the dynamometer is performed, a controller 5 includes: an integral element having an integral coefficient KI for a deviation (T12r−T12) between a shaft torque command T12r and a measured shaft torque T12; a differential element having a differential coefficient KD for the measured shaft torque T12; and a proportional element KP for the measured shaft torque T12. The controller 5 obtains a torque control signal T2 by subtracting the differential element and the proportional element from the integral element. Control parameters (KI, KP, KD, f1) are determined according to control characteristic parameters (a4, a3, a2, a1) set in a function calculation section 6, inertia moments J1, J2 of the engine and the dynamometer, and spring rigidity K12 of the coupling shaft.