An X-ray fluorescence spectrometer includes: an X-ray source which irradiates a sample with primary X-rays; a light condensing device which condenses the primary X-rays to reduce an irradiation area on the sample; a detector which detects fluorescent X-rays produced from the sample irradiated with the primary X-rays; a housing which accommodates the X-ray source and the light condensing device; a temperature sensor which is disposed in at least one of the X-ray source and the periphery of the X-ray source; at least one external-air fan which is disposed on the housing, and which can exchange internal air with external air; and a control section which drives the external-air fan based on temperature information detected by the temperature sensor, to adjust the ambient temperature around the X-ray source to a constant temperature.