As described in this paper, we propose a sheet-type pressure sensor to support assistive technology for artificial knee joint replacement. The proposed pressure sensor consists of two sheets: an electrode sheet with metal wiring and a flexible polymer-based insulating layer on 80 μm polyimide film, as well as a pressure-sensitive conductive sheet that can function as a pressure-to-resistance sensor. We developed a 5 cm × 7 cm pressure sensor sheet with 116 sensing points. The multiple sensing sheet is expected to monitor the pressure distribution in an artificial knee joint during total knee arthroplasty to improve patients' quality of life.