An atomizer includes: an enclosed reservoir defining an inner space adapted to receive a liquid therein; a jet nozzle provided in the inner space for passage of an air jet therethrough and formed with an air outlet; a jacket sleeved around the jet nozzle to define a fluid-introducing gap therebetween, the fluid-introducing gap being in fluid communication with the inner space; an air inlet conduit extending into the inner space, disposed above and connected to the jacket, and including a bottom wall having a jet-blocking portion aligned with the air outlet of the jet nozzle in a jet-ejecting direction, and a plurality of through-holes disposed around the jet-blocking portion and opening in the jet-ejecting direction; and a mist-discharging conduit extending sealingly into and in fluid communication with the inner space.