A heater includes a ceramic structure; a heat-generating resistor embedded in the ceramic structure; a conductor line connected to the heat-generating resistor; a through-hole conductor having one end connected to the conductor line and the other end led out to a surface of the ceramic structure; and an electrode pad disposed on the surface of the ceramic structure so as to cover the through-hole conductor, the electrode pad being connected to the through-hole conductor. The through-hole conductor has a protrusion which protrudes outwardly beyond the surface of the ceramic structure.