Covering material, covered rectangular rlectric wire and electrical device

Provided is a covering material 10, characterized in that the covering material includes a backing 11 having an upper surface 11a and a lower surface 11b opposite to the upper surface 11a, and a viscoelastic layer 12 formed on the upper surface 11a of the backing 11, in which the covering material is a covering material for covering a rectangular electric wire, and an adhesive force of the viscoelastic layer 12 to the lower surface 11b of the backing 11 as measured by peeling at a peeling angle of 180° and a tensile rate of 300 mm/min is 0.05 N/20 mm or more and 10 N/20 mm or less. A covered rectangular electric wire includes the covering material 10 and a rectangular electric wire covered with the covering material 10. An electrical device is produced by using the covered rectangular electric wire.