1. An X-ray fluorescence analyzer comprising: a sample stage having a mounting surface on which a sample is mounted; an X-ray source configured to irradiate the sample with the primary X-rays and disposed immediately above an irradiation position of the sample; a detector configured to detect fluorescent X-rays emitted from the sample irradiated with the primary X-rays; an X stage configured to move the sample stage in an X direction that is parallel to the mounting surface; a Y stage configured to move the sample stage in a Y direction that is parallel to the mounting surface and perpendicular to the X direction; a θ stage configured to have a rotation center at the center of the mounting surface and to rotate the sample stage around a rotation axis perpendicular to the mounting surface; and a shielding container configured to accommodate the sample stage, the X-ray source, the detector, the X stage, the Y stage, and the θ stage, wherein the irradiation position with the primary X-rays is set at an offset position from a movement center of the X stage and the Y stage, wherein an irradiation area that is irradiatable with the primary X-rays is set to a selected segmented area, in which the irradiation position is disposed, from among segmented areas that are defined by segmenting the surface of the sample into four parts with a virtual segment line in the X direction and a virtual segment line in the Y direction passing through the movement center when the X stage and the Y stage are moved in a state in which the θ stage is not moved, and wherein the θ stage is configured to switch the selected segmented area as the irradiation area into any one of the segmented areas by rotating the sample stage by every 90 degrees.