Patent ID: 7595714

Claim:
An ignition coil comprising: a primary coil ( 14 ); a secondary coil ( 16 ) disposed on an outer circumferential side of the primary coil ( 14 ) and configured to be boosted by mutual induction with the primary coil ( 14 ); an outer periphery core ( 18 ) having an opposing surface ( 183 ), which is opposed to an outer peripheral surface ( 160 ) of the secondary coil ( 16 ); and an insulating member ( 20 ) disposed between the outer peripheral surface ( 160 ) and the opposing surface ( 183 ), wherein the secondary coil ( 16 ) and the outer periphery core ( 18 ) are arranged such that B is larger than A, given that A is a shortest distance between the outer peripheral surface ( 160 ) and the opposing surface ( 183 ) and B is a shortest distance between the outer peripheral surface ( 160 ) and an outer edge ( 183 a , 183 b ) of the opposing surface ( 183 ).