Provided is a flame-retardant polyolefin resin composition, which contains 1 to 100 parts by weight of an organic phosphorus compound (component B) represented by the following formula (1) per 100 parts by weight of the polyolefin resin (component A), realizing high flame retardancy, high heat resistance and excellent physical properties.

wherein X 1 and X 2 , which may be the same or different, are aromatic-substituted alkyl groups, represented by the following formula (2):

wherein AL is a branched or linear aliphatic hydrocarbon group having 1 to 5 carbon atoms, Ar is a phenyl group, a naphthyl group, or an anthryl group optionally having a substituent in an aromatic ring, n represents an integer of 1 to 3, and Ar can be bonded to any carbon atom in AL.