This study describe an experiment measuring the moment of inertia of an electric powered wheelchair (EPW) using a torsional pendulum method. Inertia of the wheelchair is an important factor for control, which is a key issue in wheelchair driving. The experimental test platform consisted of a bottom circular wood plate, an upper metal plate, and four ropes. Materials with known moments of inertia such as the metal disk and cylinder were used to test the accuracy of the system. The EPW used in the experiment was Invacare G3 Torque SP Storm Series. The measured result of the moment inertia of the wheelchair was 5.2280 kg.m(2) and the errors of the system are less than 10% even when the object is only 25lbs. The results are consistent when compared with other approximate methods. In addition, the experimental method could be used to measure the moment of inertia of manual wheelchairs and other irregular objects.