Disclosed herein is a portable air purifier. The portable air purifier includes: a body; first to third accommodation portions configured to have respective open top surfaces in order to separately accommodate a battery, an air compressor, and water; first to third covers configured to selectively open and close the respective open top surfaces of the first to third accommodation portions; an air inlet connected to the lower portion of the second accommodation portion, and configured to accommodate a pre-filter; a siphon pipe positioned upright inside the water of the third accommodation portion, and configured such that the top thereof is connected to the air outlet of the air compressor; a cannula installed on the top of the third accommodation portion, and configured to supply purified, humidified air to a user; and a power switch configured to control the amount of air to be supplied.