To effectively transmit heat by a simple structure and to improve workability in assembling by directly mount a power switching unit on a wall protruded in the axial direction from the bottom surface in a housing.

A distributor integrated with an ignition coil detects a change in magnetic flux caused by the rotation of a signal rotor 6 mounted on a shaft 1 by an electromagnetic pickup opposite to the signal rotor 6 and induces voltage in the electromagnetic pickup. A power switching unit 11 controls a first current from a battery passing through the first coil of an ignition coil 14 mounted on an inner stay 13 and produces a high voltage in a second coil when the first current is shut off. The power switching unit 11 is mounted directly on a wall surface 21 protruded toward a cap side from the bottom surface 20 in a housing 2, whereby heat generated by the power switching unit 11 is effectively transmitted to the outer periphery of the housing 2.