| 摘要 |
A spark plug (1) includes a ceramic insulator (2) having an axial bore (4) extending in the direction of an axis (CL1) and a terminal electrode (6) inserted into the axial bore (4). The terminal electrode (6) includes a rodlike leg portion (6A) inserted into the a rear end portion of the axial bore (4) and a head portion (6B) exposed at the rear end of the ceramic insulator (2). A front end subportion of the leg portion (6A) of the terminal electrode (6) is fixed to the ceramic insulator (2), and the leg portion (6A) has a length of 35 mm or more along the axis (CL1). Additionally, the center of gravity of the terminal electrode (6) is located in the interior of the ceramic insulator (2). Thus, in the spark plug (1) having the terminal electrode (6) whose leg portion (6A) is relatively long, breakage of the terminal electrode (6) can be more reliably prevented. |
