An operation method of an aerosol generating device , the method comprising: detecting whether an aerosol generating substance is inserted into a cavity based on an amount of change in inductance; heating the aerosol generating substance based on the aerosol generating substance being inserted into the cavity ; detecting whether the aerosol generating substance is separated from the cavity based on the amount of change in the inductance while the aerosol generating substance is being heated; and, based on determining that the aerosol generating substance is separated from the cavity , stopping the heating of the aerosol generating substance based on the amount of change in the inductance during a pre-set separation time, wherein the detecting of whether the aerosol generating substance is separated from the cavity comprises: correcting an inductance output value of a substance detector configured to detect a presence of the aerosol generating substance; calculating the amount of change in the inductance based on a corrected inductance output value; and determining that the aerosol generating substance is separated from the cavity based on the amount of change in the inductance being less than or equal to a pre-set lower-limit threshold value, wherein the correcting of the inductance output value comprises: decreasing the inductance output value of the substance detector in response to an increase in a temperature of a heater configured to heat the aerosol generating substance. detecting whether an aerosol generating substance is inserted into a cavity based on an amount of change in inductance; heating the aerosol generating substance based on the aerosol generating substance being inserted into the cavity ; detecting whether the aerosol generating substance is separated from the cavity based on the amount of change in the inductance while the aerosol generating substance is being heated; and, based on determining that the aerosol generating substance is separated from the cavity , stopping the heating of the aerosol generating substance based on the amount of change in the inductance during a pre-set separation time, wherein the detecting of whether the aerosol generating substance is separated from the cavity comprises: correcting an inductance output value of a substance detector configured to detect a presence of the aerosol generating substance; calculating the amount of change in the inductance based on a corrected inductance output value; and determining that the aerosol generating substance is separated from the cavity based on the amount of change in the inductance being less than or equal to a pre-set lower-limit threshold value, wherein the correcting of the inductance output value comprises: decreasing the inductance output value of the substance detector in response to an increase in a temperature of a heater configured to heat the aerosol generating substance. correcting an inductance output value of a substance detector configured to detect a presence of the aerosol generating substance; calculating the amount of change in the inductance based on a corrected inductance output value; and determining that the aerosol generating substance is separated from the cavity based on the amount of change in the inductance being less than or equal to a pre-set lower-limit threshold value, wherein the correcting of the inductance output value comprises: decreasing the inductance output value of the substance detector in response to an increase in a temperature of a heater configured to heat the aerosol generating substance. <EOS>