Disclosed are a phosphor sheet capable of improving color purity of each of RGB reproduced through a color filter, a white light source device including the phosphor sheet, and a display device including the white light source device. The disclosed phosphor sheet is a phosphor sheet for converting LED light into white light, including: a phosphor layer containing at least a phosphor and a resin; and a pair of transparent substrates sandwiching the phosphor layer, in which the phosphor sheet includes a coloring material having an absorption maximum wavelength of at least one of from 480 nm to 510 nm or from 570 nm to 620 nm.