To prevent poor conduction due to freezing of condensation by controlling the condensation at a contact section of an engine starting device.
The engine starting device 1 is driven by an electric motor 2. A switch part 42 controlling electric power supply to the electric motor 2 includes a first conduction plate 41a connected to a motor side, a second conduction plate 41b connected to an electric power source side, and a switch plate 43 changing over conduction and insulation between the first and the second conduction plate 41a, 41b. A condensation inducing part 95 connecting a mountain part 97a and valley part 97b in a sawtooth shape is provided at a side edge 96 separate from a contact touch part 94 of the second conduction plate 41b. Since heat capacity is low and heat is easily dissipated, condensation easily occurs at a part end surface 98 of the contact touch part 94 and an edge 99. Condensation occurs at the condensation inducing part 95 earlier than the contact touch part 94.
HOSHI TAKAYUKI
SUDO CHIEKO
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