Objects of the present invention are to provide a phosphoric acid-esterified fine cellulose fiber of which slurry shows superior transparency, and to provide a method for producing a phosphorylated fine cellulose fiber showing superior transparency with good efficiency and high yield. According to the present invention, there is provided a phosphoric acid-esterified fine cellulose fiber, of which 0.2 mass % aqueous dispersion shows a solution haze of 15% or lower.