Knee osteoarthritis patients have pain in their knee and it can become difficult to walk depending on the progress of symptoms. After performing chondrocyte implantation, it is necessary to reduce the load on the knee joint until the implanted cartilage is integrated. The purposes of this study were to develop a device that enables the user to walk and reduced the weight on the knee joint and to confirm basic performance of the device through experiments. The device was composed of a seat for supporting the body weight of the user, a prosthetic knee, and the floor reaction force sensor shoes. Experiments were conducted to confirm the basic performance of the device. As a result, an able-bodied participant who wore the device was able to walk while unloading two-thirds of their body weight onto their knee. As a result of gait analysis, it was found that the gait did not change significantly even when the device was worn.