Glow plug fitted with combustion pressure detection sensor

A glow plug having a leading front end and an opposing rear end, and including a combustion pressure detection sensor, the glow plug comprising:

• a housing having a cylindrical shape which houses a heater having a pillar shape, a leading end of the heater protruding from a leading end of the housing;
• and
• a sensor that detects the combustion pressure based on displacement of the heater by action of the combustion pressure,
• the glow plug having an annular gap between an inner peripheral surface of a leading end part of a predetermined range from the leading end of the housing toward a rear part thereof and an outer peripheral surface of the heater, and
• a deformable seal member allowing for displacement of the heater is provided in the annular gap so as to divide the annular gap into front and rear sides,
• wherein, in the outer peripheral surface of the heater, in a part facing the inner peripheral surface of the leading end part of the housing interposed in the annular gap, a convex portion protruding outward in a radial direction is formed so as to maintain a gap with the inner peripheral surface,
• wherein the leading end of the convex portion is formed so as to be located to the front of the leading end of the housing,
• wherein in the seal member, an inner periphery edge portion at the outer peripheral surface side of the heater has a cylindrical portion bent and extended frontwards, the cylindrical portion being fixed to the outer peripheral surface of the heater, and
• wherein in a radial direction, an outermost peripheral portion of the convex portion is located outside the outer peripheral portion of a leading end of the cylindrical portion of the seal member.