In a light source in which a semiconductor luminescence element and a phosphor are combined, red light having high color purity is efficiently radiated. The light source includes: a semiconductor luminescence element; a fixed or rotatable first wavelength converting unit; and a rotatable second wavelength converting unit. The second wavelength converting unit includes: a second wavelength converting region that absorbs output light emitted from the semiconductor luminescence element and radiates light having a second wavelength different from that of the output light; and a transmission region that transmits the output light. The first wavelength converting unit absorbs the output light to radiate light having a first wavelength longer than the second wavelength of the light, and the light having the first wavelength is transmitted through the transmission region.