A 33-year-old man was referred to our hospital with chief complaints of fever, dizziness, and headache. Although he had recurring fever and dizziness for 7 months, neurological examination, magnetic resonance imaging, computed tomography, electrocardiograms, and blood tests were normal. He was diagnosed with functional hyperthermia, cervical vertigo, and tension headache and was treated with oral medication and physical therapy. After treatment, the dizziness and headache resolved; however, the fever and anxiety did not. During follow-up, he noticed differing results from different electronic thermometers. The physician decided to use an accurate analog thermometer, a gallium thermometer, in combination with the other thermometers. The results differed significantly among the thermometers, and the electronic thermometer readings were found to be inappropriately high. The physician made a diagnosis of pseudo-fever, and the patient recognized that the gallium thermometer's results were the most accurate reflection of his physical condition, resolving his anxiety.