A pencil type glow plug (10) to be arranged in the combustion chamber of air-compressing internal combustion engines has a tubular plug housing (11) in the longitudinal bore of which a pencil type glow element (16) is sealingly fixed over part of its length. An annular gap (21) is formed in a particular area located at the bottom of or facing the combustion chamber between the longitudinal bore (12) and the glow element (16) for thermally uncoupling the plug housing from the glow element.