Provided are a covered wire and a wire harness having excellent heat resistance and an excellent appearance. Provided is a covered wire including a conductor and an insulating covering, in which the insulating covering is made of a resin composition, the resin composition includes a silane graft polyolefin, an unmodified polyolefin, a modified polyolefin having one or more functional groups selected from the group consisting of a carboxy group, an ester group, an acid anhydride group, an amino group, and an epoxy group, a flame retardant, a cross-linking catalyst, and zinc oxide and an imidazole-based compound, and the surface roughness Ra of the insulating covering is 4.0 μm or less.