Patients with severe mental and physical handicaps cannot adequately express their intentions. Herein, we aimed to determine the effectiveness and method of gaze input devices as a means for children with severe disabilities express their intentions. Two children with severe physical and mental disabilities performed the activities, with the gaze input device, three times per session for a total of 10 days. The results were analyzed quantitatively and qualitatively. Although there was no clear change in the effectiveness of eye movements as a means of expressing one’s intentions by using the gaze input device, the observed state could have affected awareness. This was the initial stage of communication performed. In conclusion, gaze input devices help children with severe mental and physical disabilities express their intentions by grading tasks and setting environments according to their development level.