Provided is a Li-solid-solubilized ±-SiAlON phosphor containing Li + solid-solubilized for stabilization of the structure which is higher in luminous efficiency than any phosphor currently available and a light-emitting element and a lighting device comprising the same. An Eu-activated Li-solid-solubilized a-SiAlON, having a lattice constant a of 0.7820 to 0.7835 nm, a lattice constant c of 0.5645 to 0.5670 nm, an oxygen content of 0.4 to 1.2 mass %, and an europium (Eu) content of 0.3 to 1.2 mass%, and emitting a light having a peak wavelength of 580 to 595 nm in the fluorescence spectrum obtained when it is excited by a monochromatic light having a peak wavelength in the range of 450 to 460 nm.