A composition for an electric wire coating material that has excellent damage resistance, low-temperature flexibility, and tear resistance, and an insulated electric wire in which this composition is used. The composition for an electric wire coating material containing polyvinyl chloride contains a plasticizer in an amount of 15 to 30 parts by mass and a thermoplastic polyurethane elastomer in an amount of 0.01 to 10 parts by mass, with respect to 100 parts by mass of the polyvinyl chloride. An insulated electric wire is obtained by coating an outer circumference of a conductor with an insulating coating layer, using this composition for an electric wire coating material in an electric wire coating material.