| 摘要 |
PROBLEM TO BE SOLVED: To provide a multi-pole spark plug which does not depend on the directional property of a ground electrode after assembling and which is superior in ignitability. SOLUTION: These multi-pole spark plugs 10, 20 have an insulating insulator 2, the central electrode 3 arranged and installed at this insulating insulator 2, and two ground electrodes 4a, 4b so that opposing faces 41a, 41b to oppose to the outer circumferential face 31 of the central electrode 3 are formed, and among respective gaps (G) of respective spark discharge gaps, differences between the greatest gap and the smallest one are made to be 0.3 mm or less.
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