An illuminator comprising: a first light source unit that includes a plurality of first solid-state light sources and outputs a plurality of first light beams (BL1s); a second light source unit that includes a plurality of second solid-state light sources and outputs a plurality of second light beams (BL2p) having a polarization state different from a polarization state of the plurality of first light beams; a polarization combining element that combines the plurality of first light beams with the plurality of second light beams; a polarization state conversion element (23; 123) on which the combined light produced by the polarization combining element is incident; a polarization separation element that separates the combined light having passed through the polarization state conversion element into first light and second light having a polarization state different from a polarization state of the first light; a wavelength conversion element that converts the first light into third light; and a driver that is configured to change a positional relationship between the polarization state conversion element and an optical axis of the combined light in a first direction, wherein the second light and the third light are outputted as illumination light, the polarization state conversion element includes a plurality of retardation elements that are separate from one another and arranged in the first direction, the first light source unit and the second light source unit are so configured that a plurality of first regions through which the plurality of first light beams pass and a plurality of second regions through which the plurality of second light beams pass are alternately arranged in the first direction in the polarization state conversion element, and the pitch at which the plurality of retardation elements are arranged in the first direction is the same as the pitch at which the plurality of first regions are arranged in the first direction and the pitch at which the plurality of second regions are arranged in the first direction. a first light source unit that includes a plurality of first solid-state light sources and outputs a plurality of first light beams (BL1s); a second light source unit that includes a plurality of second solid-state light sources and outputs a plurality of second light beams (BL2p) having a polarization state different from a polarization state of the plurality of first light beams; a polarization combining element that combines the plurality of first light beams with the plurality of second light beams; a polarization state conversion element (23; 123) on which the combined light produced by the polarization combining element is incident; a polarization separation element that separates the combined light having passed through the polarization state conversion element into first light and second light having a polarization state different from a polarization state of the first light; a wavelength conversion element that converts the first light into third light; and a driver that is configured to change a positional relationship between the polarization state conversion element and an optical axis of the combined light in a first direction, wherein the second light and the third light are outputted as illumination light, the polarization state conversion element includes a plurality of retardation elements that are separate from one another and arranged in the first direction, the first light source unit and the second light source unit are so configured that a plurality of first regions through which the plurality of first light beams pass and a plurality of second regions through which the plurality of second light beams pass are alternately arranged in the first direction in the polarization state conversion element, and the pitch at which the plurality of retardation elements are arranged in the first direction is the same as the pitch at which the plurality of first regions are arranged in the first direction and the pitch at which the plurality of second regions are arranged in the first direction.