Abstract: A circuit disconnecting member that blows on receiving radiant heat generated by heat generation of a motor circuit is connected to a motor circuit, the blowing temperature being a temperature lower than a thermal breakdown temperature of a combustible substance around the motor circuit, whereby the motor circuit is shut off, when the peripheral part of the motor circuit generates heat, to stop heat generation before an insulation cover or a contact case is subjected to thermal connection breakage. An engine starting device is prevented from being subjected to a thermal breakdown by a small-size, simple construction and an inexpensive technique without impairing the mounting layout properties of the starting motor and the performance within the rated use.

Abstract: A circuit disconnecting member that blows on receiving radiant heat generated by heat generation of a motor circuit is connected to a motor circuit, the blowing temperature being a temperature lower than a thermal breakdown temperature of a combustible substance around the motor circuit, whereby the motor circuit is shut off, when the peripheral part of the motor circuit generates heat, to stop heat generation before an insulation cover or a contact case is subjected to thermal connection breakage. An engine starting device is prevented from being subjected to a thermal breakdown by a small-size, simple construction and an inexpensive technique without impairing the mounting layout properties of the starting motor and the performance within the rated use.