A cellulose fiber reinforced resin composition, containing a thermoplastic resin containing a polyolefin resin and an alkoxysilane-modified polypropylene resin, and 101 to 400 mass parts of cellulose fibers based on 100 mass parts of the thermoplastic resin, wherein, in planar view observation, a total area of aggregates of the cellulose fibers is 1.00 mm2/cm2 or less; a method of producing this cellulose fiber reinforced resin composition; and a cellulose fiber reinforced resin formed body.