An aerosol-generating device is disclosed. The aerosol-generating device of the present disclosure includes a body having therein an elongated hollow portion; a cartridge coupled to the body and comprising: a first chamber configured to store a liquid; a second chamber disposed adjacent to the first chamber; a wick disposed in the second chamber to receive the liquid from the first chamber; and a heater configured to heat the wick; a connection passage configured to allow communication between the hollow portion and the second chamber of the cartridge; an inflow passage formed at the cartridge to allow external air to enter the second chamber; and a sensor disposed adjacent to the inflow passage and configured to sense flow of air passing through the inflow passage.