The present disclosure provides a resinous material for covering electric wire having all required properties meeting or exceeding a certain standard, produced using a cyclic olefin-derived resin, and electric wires manufactured using the resinous material for covering electric wire, and flame-retardant cables. The resinous material including (A) an olefin-derived resin, (B) an elastomer resin, (C) a cyclic olefin-derived resin having a glass transition point of from 120° C. to 170° C., and (D) a flame retardant, the resinous material having: a content of the component (D) of from 60 parts by mass to 150 parts by mass relative to 100 parts by mass of the total contents of the components (A), (B) and (C); a tensile elongation of no less than 250%; and a heat deformation of no greater than 40%.