A 64-year-old man working as a drafting technician presented to the emergency department with a fever and abnormal speech and behavior for four days. On examination, he was suspected of having jargon aphasia and mildly impaired consciousness. Brain magnetic resonance imaging showed high signal intensity on diffusion weighted images in the left temporal lobe and insula. Although the cerebrospinal fluid (CSF) cell count was only slightly elevated (8/mm3), we suspected herpes simplex virus encephalitis (HSVE) based on the history and imaging findings. Acyclovir was immediately started on the day of admission. Six days after admission, an alternating level of consciousness was observed. Electroencephalogram revealed non-convulsive status epilepticus, and antiepileptic drugs were started. Eight days after admission, the CSF HSV real-time polymerase chain reaction (RT-PCR) on the day of admission proved positive, and he was diagnosed with HSVE. Even after the RT-PCR became negative, sensory aphasia persisted. However, his aphasia improved to anomic aphasia after speech therapy and he restarted working 18 months after the onset. Despite the recent advent of multiplex PCR testing, such advanced testing is not always available everywhere. This case highlights the importance of early suspicion and therapeutic initiation for a better neurological outcome in HSVE.