| 主权项 |
1. A spark plug comprising:
a center electrode extending in a direction of an axial line; an insulator having an axial hole which extends in the direction of the axial line and in which the center electrode is disposed; and a metallic shell disposed around the insulator, wherein the metallic shell has a first ground electrode which is electrically connected to the metallic shell and has a first surface facing a side surface of the center electrode in a radial direction so as to form a first gap, and a second ground electrode which is electrically connected to the metallic shell and has a second surface facing the side surface of the center electrode in the radial direction so as to form a second gap; a relation 60°≦θ≦150° is satisfied, where θ is a smaller one of angles formed between a first line connecting the axis and a center of the first surface and a second line connecting the axial line and a center of the second surface when viewed from a forward end side toward a rear end side in the direction of the axis; and the metallic shell has a specific plane which bisects the metallic shell such that all the ground electrodes are located on one side of the plane, wherein at a position in the direction of the axis at which the first surface and the second surface face each other, the center electrode has an outer diameter greater than largest widths of the first surface and the second surface. |
