An ignition coil (1) comprises a case (2), a core (22) disposed in the case, a primary spool (25) substantially coaxially disposed on the outer periphery of the core in the case, a primary coil (26) wound on the primary spool, a secondary spool (23) substantially coaxially disposed on the outer periphery of the core in the case, a secondary coil (24) wound on the secondary spool, a resin insulator (5) filled into the case, wherein of the primary and secondary spools, the secondary coil and the core and/or the spool between the secondary and primary coils is made of a base resin whose adhesive force on resin insulation material is less than that of polybutylene terephthalate and whose breakdown voltage is greater than that of polyphenylene sulfide.