A dynamometer is a device for measuring force, moment of force (torque), or power. There are several types of dynamometers. We developed chassis type and inertial type wheelchair dynamometer. The inertial dynamometers should be determined the inertia and resistance. Therefore, we designed calibrating devices and analytical models for static and dynamic calibration of the developed dynamometer. The linear equations for the transducers to convert the outputs from the sensors into the torque were determined by 50.98v-2.44 (right sensor) and 50.16v-3.25 (left sensor) respectively. As a results of the dynamic calibration, the moment of inertia of the fixed part of the roller system was estimated at 0.0344 kg·m2 by using the mobile disk with 0.028 kg·m2. The total resistive torque, when the weight of user-wheelchair system was 77.5kg, estimated at -2.487(±0.161)Nm. Although the developed system has some inevitable limitations, it is expected that the data from the dynamometer would be useful to investigate the kinetics of the wheelchair propulsion.