A portable nebulizer includes a nebulizer body including a nozzle hole and an atomizer plate positioned in the nozzle hole, and a dust shield coupled to the nebulizer body and movable relative to the nebulizer body between a dust protection position where the dust shield shields the nozzle hole of the nebulizer body and an open position where the dust shield is kept away from the nozzle hole of the nebulizer body, thus, the dust shield is capable of protecting the nozzle hole of the portable nebulizer against environmental contamination.