An intake air heating control device for a gas turbine, comprising: a heat exchanger for heating air, which is taken into the gas turbine, by a heating medium; a control valve for controlling an amount of the heating medium, which is supplied to the heat exchanger, by having a valve opening degree thereof controlled; a thermometer for measuring a temperature of air (A') which has been heated by the heat exchanger and is taken into the gas turbine; and a control device for controlling the valve opening degree of the control valve so that a measured temperature measured by the thermometer becomes a preset target temperature, characterized in that the control device comprises a deviation computing section for obtaining a deviation temperature (At) being a deviation between the target temperature and the measured temperature, and a proportional plus integral computing section for performing proportional plus integral computation of the deviation temperature (At) to obtain a valve opening degree PI correction command, a valve opening degree command computing function section for outputting a valve opening degree command (d) whose value increases when a number of revolutions of the gas turbine increases, an inlet guide vane correction coefficient computing function section for outputting an inlet guide vane correction coefficient (c) whose coefficient value increases when an opening degree of an inlet guide vane of the gas turbine heightens, a multiplying section for multiplying the valve opening degree command (d) by the inlet guide vane correction coefficient (c), and outputting a valve opening degree prior command (f), and an adding section for adding the valve opening degree prior command (f) to the valve opening degree PI correction command, and outputting a corrected valve opening degree command, and controls the valve opening degree of the control valve in accordance with a magnitude of the corrected valve opening degree command. a heat exchanger for heating air, which is taken into the gas turbine, by a heating medium; a control valve for controlling an amount of the heating medium, which is supplied to the heat exchanger, by having a valve opening degree thereof controlled; a thermometer for measuring a temperature of air (A') which has been heated by the heat exchanger and is taken into the gas turbine; and a control device for controlling the valve opening degree of the control valve so that a measured temperature measured by the thermometer becomes a preset target temperature, characterized in that the control device comprises a deviation computing section for obtaining a deviation temperature (At) being a deviation between the target temperature and the measured temperature, and a proportional plus integral computing section for performing proportional plus integral computation of the deviation temperature (At) to obtain a valve opening degree PI correction command, a valve opening degree command computing function section for outputting a valve opening degree command (d) whose value increases when a number of revolutions of the gas turbine increases, an inlet guide vane correction coefficient computing function section for outputting an inlet guide vane correction coefficient (c) whose coefficient value increases when an opening degree of an inlet guide vane of the gas turbine heightens, a multiplying section for multiplying the valve opening degree command (d) by the inlet guide vane correction coefficient (c), and outputting a valve opening degree prior command (f), and an adding section for adding the valve opening degree prior command (f) to the valve opening degree PI correction command, and outputting a corrected valve opening degree command,