A new liquid phase epitaxy (LPE) method, which can control impurity concentration by volatilization of impurities from the growth solution under reduced pressure, has been developed. Using this LPE method, high‐efficiency GaP pure green light‐emitting diodes, of which the peak wavelength is 555 nm, has been obtained. The average efficiency for a epoxy‐encapsulated diode is 0.1% and the maximum efficiency is 0.14% at 16 A/cm2.