Remains constant in the engine control device of the hybrid electric vehicle, the reset time (Reset Time) and the waveform when the power is applied due to the application when the ignition key of the spare battery power source to the square wave to maintain a constant communication start time of the other controlled device and then off of the ignition key, so that the reset signal is not generated by preventing recognizes an oN signal of the ignition key generated at the power supply latch time to prevent the erroneous operation between the MCU (Motor Control Unit) and BMS (Battery Management System) not generated that, When the secondary battery power source (B + PERM) is supplied by generating a standby power supply of 5V standby power generator for supplying power to the normal state, each control unit of the peripheral unit, the ignition in the state of standby by the standby power supply of the 5V unit key signal on the time latch voltage stabilization to from to after detecting the off to the point where the power latch ends maintain the 5V supply to the EMS-related sensors and actuators to knock the operations, the first secondary battery (B + PERM ) of it includes if a reset occurs to output the reset signal to the active "low" as the power is turned on of the ignition key signal that is newly detected after the power latch end supply in accordance with the off-detection of the start point and an ignition key signal is applied. Hybrid electric vehicle, the power latch, a reset signal, MCU