Crutches are often used for rehabilitation of the injured. For safety of patients, it is important to measure and analyze how patients walk with crutches, and to instruct them in the early stage is necessary. Measurement of motion of a crutch usually requires several external sensors, for example a motion capturing system which consists of several cameras and a computer. This takes a great deal of effort. Therefore, the authors developed a system which measures the angle of a crutch and the angular velocity of a crutch. Based on these sensors, the motion of a crutch can be estimated without external sensors. Through experiment, the authors have confirmed that the developed system can estimate and visualize the motion of a crutch based on only internal sensors embedded in the crutch.