A cellulose-fiber-dispersing polyolefin resin composite material, containing a polyolefin resin containing a polypropylene resin, and a cellulose fiber dispersed in the polyolefin resin, in which a proportion of the cellulose fiber is 1 mass part or more and 70 mass parts or less in a total content of 100 mass parts of the polyolefin resin and the cellulose fiber, and the polyolefin resin satisfies the expression: Mz/Mw≥4, which is a ratio of Z-average molecular weight Mz to weight-average molecular weight Mw to be obtained by a gel permeation chromatography measurement; a pellet or a formed body using this composite material; and a production method for the composite material.