Good accuracy for the clinical diagnosis of frontotemporal lobar degeneration (FTLD) by specialists in an early onset dementia clinic has been reported. To assess the diagnostic accuracy of FTLD in an entire population, without restrictions related to patient age or diagnosing physician. Volumes of the "Annual of the Pathological Autopsy Cases in Japan," with reports of 130,105 autopsies throughout Japan from 2007 to 2016, were descriptively analyzed. There were 219 patients with clinical and/or pathological diagnoses of FTLD. The sensitivity and specificity were 24.5% and 76.9%, respectively. Age at death for pathologically confirmed patients was 76.3 ± 11.6years (mean ± standard deviation). Overlooked patients died significantly older than patients with an accurate clinical diagnosis. Clinical diagnoses of FTLD had low sensitivity. Furthermore, the age at death of pathologically confirmed patients suggests that FTLD affects a wide age range and is not restricted to presenile individuals.