An X-ray fluorescence spectrometer includes: a sample stage configured to place a sample thereon; an X-ray source configured to irradiate the sample with primary X-rays; a detector, which is configured to detect fluorescent X-rays produced from the sample irradiated with the primary X-rays, and which includes an X-ray incident window formed by a window material through which fluorescent X-rays is transmittable; and a gas blowing mechanism configured to blow a gas to at least one of an outer surface of the X-ray incident window and the sample stage.