Abstract: The present invention provides a method for controlling idle speed of an engine in an engine idle control system including a battery voltage sensor, a coolant temperature sensor, a sensor for detecting an amount of alternator generation, an engine speed sensor, an ISC controlling an amount of air supplied to the engine in an idle state, and an ECU that is supplied with detected values from the sensors and outputs a control signal to the ISC based on the detected value being supplied, the method comprising the steps of: (a) determining whether a time elapsed after starting is within a predetermined range; and (b) performing feedback control of engine speed in a state of stopping ISC control according to the amount of alternator generation when the time elapsed after starting is within the predetermined range.