摘要 |
A spark plug having sufficient durability for an internal combustion engine is provided by restraining a sharp increase in resistance of a resistor while the size of the spark plug is reduced. The spark plug comprises an insulator having an axial hole, a metallic shell provided on the outer circumference of the insulator, a center electrode inserted into a front end portion of the axial hole, a terminal electrode inserted into a rear end portion of the axial hole, and a ground electrode. A circular columnar resistor is disposed within the axial hole between the center electrode and the terminal electrode, thereby electrically connecting the center electrode and the terminal electrode. The resistor is composed of carbon black serving as a conductive material, a glass powder, and ceramic particles. The ceramic particles have a maximum particle size of 0.5 μm or less.
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