A vehicle engine starting system that drives a starter motor engaged to start an engine by using a lithium secondary battery as a power source comprises a voltage sensor that detects a voltage at the secondary battery and a control device that allows power to be discharged from the secondary battery to the starter motor if the voltage at the secondary battery detected by the voltage sensor is equal to or higher than a predetermined value and disallows a discharge from the secondary battery to the starter motor if the voltage at the secondary battery detected by the voltage sensor is lower than the predetermined value.