According to the 2010 neuroresuscitation guideline, status epilepticus (SE) is a critical condition that causes respiratory and circulation dysfunction, including "acute consciousness disturbance" and "elevated intracranial pressure." There are two types of SE: general convulsive SE (GCSE) and nonconvulsive SE (NCSE). GCSE is easily diagnosed because the patients show continuous convulsions. In contrast, NCSE can only be diagnosed by electroencephalography (EEG), which can delay diagnosis. Moreover, GCSE and NCSE occasionally manifest in the same patient and alternate. Here, we describe the case of a 64-year-old male patient who experienced losses of consciousness mimicking stroke. We could not diagnose these episodes as NCSE until the patient had a general continuous convulsion. In this case, the delayed diagnosis of NCSE resulted in uncontrollable GCSE that required intensive management, including mechanical ventilation under sedation. It is important to recognize that NCSE can cause consciousness disturbance and to initiate treatment as soon as possible to improve patient prognosis. This could be achieved by performing an EEG earlier, such as at the scene of emergencies.