| 摘要 |
A spark plug includes a center electrode, a ground electrode opposing the center electrode in such a manner as to define a spark discharge gap between the center electrode and the ground electrode, and an igniter fixed to at least one of the center electrode and the ground electrode in such a manner as to face the spark discharge gap. The igniter is composed of a metallic material whose principal component is one of a platinum and an iridium. One type of the metallic material of the igniter contains an oxygen content of not more than 120 ppm. Another type of the metallic material of the igniter has a crystal grain of not less than 50 mum in mean diameter, and contains the oxygen content of not more than 300 ppm.
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