Body accelerations of crutch users are considerable factors for an evaluation of the crutch walk stability. In this paper, body parts motions and body accelerations of crutch users were measured, and their relationship was discussed. Based on the discussion, an estimation method of body accelerations was proposed, i.e., it was expected that body accelerations can be estimated from body parts motions by using the derived method. Several participants' crutch walks were measured, and the proposed estimation method was applied for the next measurements. In the experiments, body parts motions of crutch users were measured by Kinect sensor. Since several sensors are embedded in Kinect sensor, it can measure the transitions of body parts without any other devices. Finally, it was confirmed that body parts motions can be measured by the Kinect sensor, and the body accelerations can be estimated from the measured body parts motions.