The present invention provides a steering wheel and a heater unit used for the steering wheel that does not give discomfort to a user when operating the steering wheel. A heater unit 31 is comprised of a substrate 10 made of a polymeric foam; and a cord-shaped heater 1 arranged on the substrate 10, wherein a thickness of the substrate 10 is thinner at a portion on which the cord-shaped heater 1 is arranged than other area so that the portion is formed along a shape of the cord-shaped heater 1 and the heater unit 31 is approximately flat. A steering wheel, comprised of the above described heater unit; a wheel core material; and a covering material, wherein the heater unit is arranged between the wheel core material and the covering material.