According to the present invention, provided is a heater including a heat generating member being conductive and configured to radiate heat rays by being fed with electric power, a tubular member constituted by a metal and accommodating the heat generating member, and an intermediate member arranged between the heat generating member and the tubular member and constituted by an electrically insulating material, wherein the intermediate member is arranged and/or configured to allow, among the heat rays radiated from the heat generating member, at least light having a wavelength of from 1 μm to 2 μm to pass through the intermediate member to reach the tubular member.