This study aimed to develop a robot for effective knee joint rehabilitation. A kinematic approach was used to make exoskeleton robot joints to have the same range of motion (ROM) as that of human knee joints, and a robot exoskeleton was proposed to enable the wearer maintain a proper posture during rehabilitation therapy. This robot is generally used for the rehabilitation therapy for knee lesion patients (e.g., after knee replacement arthroplasty and cruciate ligament reconstruction), where the patients usually lie down wearing this robot. The alignment of the knees and body is a critical factor for the success of the therapy. Considering the rehabilitation therapy posture, the robot was manufactured with a kinematic structure different from that of the existing robots for knee rehabilitation therapy. In this study, the kinematic mechanism of the knee rehabilitation robot was described, and the actuator for the robot was selected by measuring the human knee joint motion and torque. Thus, an exoskeleton robot that is significantly different from the existing knee rehabilitation robots was developed.