A fluorescent substance is obtained by weighing and mixing CaS, Ga₂S₃, EuS and Ce₂S₃ in a mole ratio of (1-x):a:x:y (wherein 0.001x0.2, 0.0001y0.02 and 0.5a5) and by sintering the mixture. A light-emitting diode comprises an LED chip 2 and an LED chip sealing portion 5, made of silicone resin and including the fluorescent substance, for enclosing the LED chip 2. Hence, a fluorescent substance that is excited by light having a predetermined wavelength to emit light, a light-emitting diode having excellent luminous efficiency and luminous intensity, and a method for producing the fluorescent substance are attained by the present invention.