Abstract It is necessary for medical staff members to evaluate the computer input ability of patients with spinal cord injury (SCI) during the patients' rehabilitation. In this paper, we describe a system for measuring and evaluating the computer input ability of SCI patients. We measured the position locus of the mouse cursor when a patient operates a computer using a ball mouse. After this measurement, we calculated three time parameters to evaluate the computer input ability of the patient. In addition, we developed a new computer input device for patients, and showed by means of the three time parameters that this device was effective for some patients.