Various diseases cause consciousness disturbance, many of which are directly related to life and functional prognosis. As they often affect the respiratory and circulatory functions, differential diagnosis must be considered while stabilizing the patients. Although appropriate treatment should be started promptly after differential diagnosis, preconceptions could lead to misdiagnosis. A detailed medical interview cannot be conducted directly with the patient, which is a significant disadvantage faced by medical professionals in consciousness disturbance cases compared to other neurological disorders. Therefore, careful physical examination and diagnosis are important. At the same time, differential diagnosis may change over time, and follow-up examinations are necessary. Here, we would like to report three emergency cases of consciousness disturbance.