Provided is an air purifier with which it is possible to improve the purifying effect. An air purifier 1 provided with: a casing 2 in which a suction port 3 and discharge ports 4, 5 are open； an air passage 8 connecting the suction port 3 and the discharge ports 4, 5； a blower 10 disposed in the air passage 8； a pre-filter 6 disposed so as to face the suction port 3； a cleaning device 30 for cleaning the pre-filter 6； and a contamination sensor for sensing the degree of contamination of air, wherein an automatic cleaning mode, in which the cleaning device 30 is driven during a first cleaning duration occurring every prescribed first period, is provided, and the cleaning device 30 is prevented from being driven when a stoppage condition, in which the degree of contamination of air is greater than a prescribed value, is fulfilled within a prescribed duration immediately before the first cleaning duration.提供可提升清淨效果的空氣清淨機。本發明的空氣清淨機1，具備吸入口3及吹出口4, 5開口的殼體2、連結吸入口3與吹出口4, 5的空氣通路8、配置在空氣通路8內的送風機10、面對吸入口3配置的前置濾網6、清掃前置濾網6的清掃裝置30、及偵測空氣中的污染度的污染感測器，其特徵在於：在每一個既定第一週期的第一清掃時期設定驅動清掃裝置30的自動清掃模式；在第一清掃時期前一刻的既定期間內滿足空氣中的污染度大於既定值的停止條件時，禁止清掃裝置30的驅動。
