A phosphor optical element includes: a base member; a phosphor-containing member that includes a transparent member containing a phosphor particle; and a cover member, wherein the base member, the phosphor-containing member, and the cover member are sequentially formed on a transparent base that is transparent to a wavelength of incident light from an excitation light source, the phosphor particle has a diameter no greater than the wavelength of the incident light, and in an arbitrary cross section of the phosphor-containing member in a direction perpendicular to a main surface of the transparent base, the phosphor-containing member has, in a direction perpendicular to the main surface of the transparent base, a thickness no greater than the wavelength of the incident light.