An ignition coil includes a primary coil, a secondary coil, a primary bobbin, a secondary bobbin, a center core, and a mold resin. The center core has a pair of collar portions protruding from a main body of the center core respectively to opposite sides in a protruding direction. The primary bobbin has a collar portion at least partially sandwiched between the collar portions of the center core and the secondary bobbin in a coil axial direction. The collar portion of the primary bobbin includes an overlapping portion that overlaps the collar portions of the center core in the coil axial direction and is bonded to the collar portions. The primary bobbin is formed of a thermoplastic resin and dispersed-phase particles dispersed in the thermoplastic resin. In the overlapping portion of the primary bobbin, there is formed a specific separating layer that separates adjacent layers in the coil axial direction.