Abstract: Provided is an aerosol generating device including a heater configured to generate an aerosol by heating an aerosol generating substance; and a controller configured to control power supplied to the heater, wherein the controller distinguishes a first section, a second section, and a third section and controls power supplied to the heater, and calculates a control reference ratio by using at least two from among the first section, the second section, and the third section and controls power supplied to the heater based on the calculated control reference ratio.