Highly convenient automobile engine starting uses an individual authentication device which utilizes biological information and provides a security function required when starting the engine, while protecting a sensor for receiving the biological information. An engine starting system can comprise an ignition switch for controlling a state of an automobile; a key for changing a state of the ignition switch; a registration key for registering biological information; a switch for starting an engine; a sensor for inputting biological information; a device for storing biological information; a collating unit for collating the inputted biological information with the stored biological information; and a lid for covering the sensor of an authentication device.