A servo motor driving a load through a long shaft or transmission system is widely used in industries. Such a system encounters performance degradation caused by non-homogeneous twist of the shaft. This phenomenon is referred to as torsional resonance. This article describes our work to suppress torsional resonance in a 2-inertia system using accelerated-proportional-integral-derivative (PIDA) controller. A system model obtained from nonparametric identification is the basis for our controller design. We have shown herein with simulation results that our proposed method is very effective for torsional resonance suppression. Fast transient and disturbance rejection can be achieved.