Red phosphor and light emission device

A method for producing a red phosphor comprising a main crystal phase having the same crystal structure as a crystal structure of CaAlSiN3, the main crystal phase represented by the general formula MAlSiN3, the method comprising:

• a mixing step of mixing raw materials;
• and
• a calcination step of calcining the raw materials after the mixing step, thereby forming the red phosphor, wherein
• M in the general formula represents an element group comprising at least three elements selected from Eu, Sr, Mg, Ca, and Ba, the element group comprising Eu, Sr, and Ca as essentials;
• in the resultant red phosphor, relative to a total content of the red phosphor, a Eu content is 4.5 mass % or more and 7.0 mass % or less, a Sr content is 34.0 mass % or more and 42.0 mass % or less, and a Ca content is 0.8 mass % or more and 3.0 mass % or less;
• and
• an internal quantum efficiency of the resultant red phosphor, as measured when the red phosphor is excited by light having a wavelength of 455 nm, is 71% or more.