Abstract: A glow plug for diesel engines in which a ceramic heater is supported, with the one end thereof cantilevered toward the outside, by the tip of a hollow holder ceramic heater is composed of a U-shaped heating portion and a pair of leads extending backwards from both ends of the U-shaped heating portion, both being formed integrally by an electrically conductive ceramic material. The outer periphery of at least one of the leads is bonded and held in the holder via an insulating layer. The rear end of the other of the leads is connected by a metallic lead wire to an external connection terminal. The ceramic heater and other component members are bonded integrally by a bonding material containing a reactive metal.