An air purifier capable of reducing time required for purification of a room without giving a feeling of discomfort to a human in the room is provided. During operation of an air purifier 1, air drawn from an inlet 3 into a casing 2 is purified by a purification device 7 and the air is blown to the outside from an outlet 4. If a user of the air purifier 1 selects a particular operation mode in which the user designates an air volume, a control device 12 performs air volume maintaining control. In the air volume maintaining control, with a volume of air blown out from the outlet 4 by the air blowing device 5 maintained constant, a speed of the air is varied by an air guiding device 8 based on a status of pollutant detection. Alternatively, the speed of the air is varied by the air guiding device 8 and the volume of the air is varied by the air blowing device 5. Consequently, a dust removal efficiency can be enhanced without giving a feeling of being blown by air to a human in a room, enabling reduction of time required for purification of the room while maintaining user comfort.