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 (13, 430, 440) 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 (13, 430, 440) 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 (13, 430, 440) configured to heat the aerosol generating substance.