A wavelength dispersive X-ray fluorescence spectrometer includes a single one-dimensional detector (10) having detection elements (7) arranged linearly, and includes a detector position change mechanism (11) for setting a position of the one-dimensional detector (10) to either a parallel position at which an arrangement direction of the detection elements (7) is parallel to a spectral angle direction of a spectroscopic device (6) or an intersection position at which the arrangement direction intersects the spectral angle direction. At the parallel position, a receiving surface of the one-dimensional detector (10) is located at a focal point of focused secondary X-rays (42). At the intersection position, a receiving slit (9) is disposed at the focal point of the focused secondary X-rays (42), and the receiving surface is located at a traveling direction side of the focused secondary X-rays (42) farther from the spectroscopic device (6) than the receiving slit (9).