An aerosol generation device comprising: a heater configured to generate an aerosol by heating an aerosol generating substrate; and a controller configured to control power to be supplied to the heater for a preheating time by a battery using a control signal, wherein the preheating time is a period of time for the heater to reach a target temperature, wherein the controller is further configured to: identify state information of the battery at a heating start time point when the heater starts to be heated, calculate a duty ratio of the control signal based on the identified state information, and adjust the duty ratio so that the power supplied to the heater is maintained at a constant value to provide a constant preheating time, even when the battery voltage drops, characterised in that the controller is further configured to: control the power to be supplied to the heater using a control signal according to a first duty ratio at the heating start time point, and when a change in the state information of the battery exceeds a preset range before the heater reaches a target temperature, calculate a second duty ratio at a time point of the change to control the power to be supplied to the heater using a control signal according to the calculated second duty ratio. a heater configured to generate an aerosol by heating an aerosol generating substrate; and a controller configured to control power to be supplied to the heater for a preheating time by a battery using a control signal, wherein the preheating time is a period of time for the heater to reach a target temperature, wherein the controller is further configured to: identify state information of the battery at a heating start time point when the heater starts to be heated, calculate a duty ratio of the control signal based on the identified state information, and adjust the duty ratio so that the power supplied to the heater is maintained at a constant value to provide a constant preheating time, even when the battery voltage drops, characterised in that the controller is further configured to: control the power to be supplied to the heater using a control signal according to a first duty ratio at the heating start time point, and when a change in the state information of the battery exceeds a preset range before the heater reaches a target temperature, calculate a second duty ratio at a time point of the change to control the power to be supplied to the heater using a control signal according to the calculated second duty ratio. identify state information of the battery at a heating start time point when the heater starts to be heated, calculate a duty ratio of the control signal based on the identified state information, and adjust the duty ratio so that the power supplied to the heater is maintained at a constant value to provide a constant preheating time, even when the battery voltage drops, characterised in that the controller is further configured to: control the power to be supplied to the heater using a control signal according to a first duty ratio at the heating start time point, and when a change in the state information of the battery exceeds a preset range before the heater reaches a target temperature, calculate a second duty ratio at a time point of the change to control the power to be supplied to the heater using a control signal according to the calculated second duty ratio.