A spark section (80) forming a spark discharge gap between the spark section and an electrode tip provided to a center electrode projects in a needle-like shape from the inner surface (33) of a ground electrode (30). The spark section (80) is formed by joining a noble metal member (81) and an intermediate member (86) to each other. The material of the intermediate member (86) is adjusted to have smaller heat conductivity than the noble metal member (81). This limits heat-drawing in a route in which heat from the noble metal member (81) escapes to the ground electrode (30) side through the intermediate member (86). As a result, the noble metal member (81) is kept at temperature higher than the temperature of structures of conventional products, so that the effect of flame quenching of the noble metal member (81) to a flame core formed in the spark discharge gap is reduced to improve ignitability.
