A light-emitting system includes an optical fiber, a first light source unit, a second light source unit, and a light-guiding member. The optical fiber includes a wavelength-converting portion containing a wavelength-converting element. The wavelength-converting element may be excited by excitation light to produce a spontaneous emission of light having a longer wavelength than the excitation light and may also be excited by an amplified spontaneous emission of light. The first light source unit makes the excitation light incident on the optical fiber. The second light source unit makes seed light, causing the wavelength-converting element that has been excited by either the excitation light or the amplified spontaneous emission of light to produce a stimulated emission of light, incident on the optical fiber. The light-guiding member guides the light coming from the optical fiber and lets the light emerge therefrom.