An idling stop apparatus to be mounted on a vehicle, comprising: a microcomputer, having an idling stop function of automatically stopping an engine of the vehicle when a predetermined stop condition is established and of automatically starting the engine when a predetermined start condition is established while the engine is stopped; a battery for supplying power to the vehicle; a detector, that detects that a reset condition for resetting the microcomputer is established; and wherein the microcomputer disables the idling stop function in case of detected reset condition; characterized in that the idling stop apparatus is further comprising: a latch circuit (3a, 3b), which comprises a Reset-Set type flip-flop and which stores the information indicating that the reset condition is established, even when the microcomputer is being reset; wherein a first voltage, the first voltage being a minimum operating voltage (Vt) of the microcomputer, is higher than a second voltage, the second voltage being the minimum operating voltage (Vu) of the flip-flop; and wherein the latch circuit (3a, 3b) outputs a signal for prohibiting the microcomputer from executing the idling stop function while the latch circuit is storing the reset information in one of both cases: when the detector detects at least that a power-supply voltage (Vcc) of the microcomputer is lower than the first voltage and is higher than the second voltage; or when, the flip-flop starts operating again upon starting of the engine, after the flip-flop stops operating when the power-supply voltage (Vcc) of the microcomputer becomes below the second voltage and when the detector detects at least that the power-supply voltage of the microcomputer is above the second voltage. a microcomputer, having an idling stop function of automatically stopping an engine of the vehicle when a predetermined stop condition is established and of automatically starting the engine when a predetermined start condition is established while the engine is stopped; a battery for supplying power to the vehicle; a detector, that detects that a reset condition for resetting the microcomputer is established; and wherein the microcomputer disables the idling stop function in case of detected reset condition; characterized in that the idling stop apparatus is further comprising: a latch circuit (3a, 3b), which comprises a Reset-Set type flip-flop and which stores the information indicating that the reset condition is established, even when the microcomputer is being reset; wherein a first voltage, the first voltage being a minimum operating voltage (Vt) of the microcomputer, is higher than a second voltage, the second voltage being the minimum operating voltage (Vu) of the flip-flop; and wherein the latch circuit (3a, 3b) outputs a signal for prohibiting the microcomputer from executing the idling stop function while the latch circuit is storing the reset information in one of both cases: when the detector detects at least that a power-supply voltage (Vcc) of the microcomputer is lower than the first voltage and is higher than the second voltage; or when, the flip-flop starts operating again upon starting of the engine, after the flip-flop stops operating when the power-supply voltage (Vcc) of the microcomputer becomes below the second voltage and when the detector detects at least that the power-supply voltage of the microcomputer is above the second voltage. a latch circuit (3a, 3b), which comprises a Reset-Set type flip-flop and which stores the information indicating that the reset condition is established, even when the microcomputer is being reset; wherein a first voltage, the first voltage being a minimum operating voltage (Vt) of the microcomputer, is higher than a second voltage, the second voltage being the minimum operating voltage (Vu) of the flip-flop; and wherein the latch circuit (3a, 3b) outputs a signal for prohibiting the microcomputer from executing the idling stop function while the latch circuit is storing the reset information in one of both cases: when the detector detects at least that a power-supply voltage (Vcc) of the microcomputer is lower than the first voltage and is higher than the second voltage; or when, the flip-flop starts operating again upon starting of the engine, after the flip-flop stops operating when the power-supply voltage (Vcc) of the microcomputer becomes below the second voltage and when the detector detects at least that the power-supply voltage of the microcomputer is above the second voltage. when the detector detects at least that a power-supply voltage (Vcc) of the microcomputer is lower than the first voltage and is higher than the second voltage; or when, the flip-flop starts operating again upon starting of the engine, after the flip-flop stops operating when the power-supply voltage (Vcc) of the microcomputer becomes below the second voltage and when the detector detects at least that the power-supply voltage of the microcomputer is above the second voltage.