The utility model discloses an ignition coil used for an internal combustion engine. Insulating resin (7) is formed in a groove (52) of a high-voltage terminal (5) in an intrusive mode. The high-voltage terminal (5) and the insulating resin (7) are integrated in a clamping mode. The high-voltage terminal (5) performs displacement along with the expansion of the insulating resin (7). Therefore, even if a shell (4) and the insulating resin (7) are expanded due to raise of temperature, relative displacement between the high-voltage terminal (5) and a secondary joint (6) is prevented or restrained, so that the contact status of the high-voltage terminal (5) and the secondary joint (6) is kept. Therefore, the situation that due to the fact that the high-voltage terminal (5) is separated from the secondary joint (6), poor conduction is generated can be prevented.