Fever is a common clinical symptom that occurs due to heat production over heat dissipation, and is caused by abnormalities in the thermoregulatory center. Non-infectious diseases are commonly seen in elderly patients with fever due to reduced heat dissipation from the skin. In addition, fever is also seen in patients with intracranial hemorrhage, who develop persistent hyperthermia because of damage to the thermoregulatory center, and in people who work in a hot environment or in a hot environment for a long time. Detailed questioning in conjunction with the medical history is needed to clarify the cause of the fever before further management can be made.