An illumination device includes: a light-emitting element that emits light in a first wavelength band; a substrate rotatable about a predetermined axis of rotation; a phosphor layer that is provided on the substrate at a first distance from the axis of rotation and excited by the light in the first wavelength band to emit light in a second wavelength band different from the first wavelength band; a scattering layer that is provided on the substrate at a second distance, different from the first distance, from the axis of rotation and on which the light in the first wavelength band emitted from the light-emitting element is incident; a first pickup optical system that is provided on the side of the phosphor layer opposite to the substrate; and a second pickup optical system that is provided on the side of the scattering layer opposite to the substrate.