Provided are: a silicon nitride powder for siliconitride phosphors with higher luminance, which can be used for a fluorescent display tube (VFD), a field emission display (FED), a plasma display panel (PDP), a cathode ray tube (CRT), a light emitting diode (LED), and the like; a CaAlSiN3 phosphor, an Sr2Si5N8 phosphor, an (Sr, Ca)AlSiN3 phosphor and an La3Si6N11 phosphor, each using the silicon nitride powder; and methods for producing the phosphors. The present invention relates to a silicon nitride powder for siliconitride phosphors, which is characterized by being a crystalline silicon nitride powder that is used as a starting material for producing a siliconitride phosphor that includes silicon element and nitrogen element but does not contain oxygen element as a constitutent element, and which is characterized by having an oxygen content of 0.2% by weight to 0.9% by weight; a CaAlSiN3 phosphor, an Sr2Si5N8 phosphor, an (Sr, Ca)AlSiN3 phosphor and an La3Si6N11 phosphor, each using the silicon nitride powder; and methods for producing the phosphors.