The invention provides a purifying device. The purifying device comprises a purifying assembly for purifying air and a dehumidifying assembly for dehumidifying, and the dehumidifying assembly is arranged at an air inlet end of the purifying assembly. Water in air is removed by the dehumidifying assembly, and humidity of air which passes through the purifying assembly is reduced, so that the air which passes through the purifying assembly is dry; the problems that an existing purifying component easily strikes arc and an ozone removing assembly goes mouldy in a humid environment are solved effectively, situations of high-voltage arc striking of the purifying assembly are reduced, meanwhile, the ozone removing assembly is not prone to going mouldy, the purifying effect of the purifying device is guaranteed, and the use performance of the air purifier is improved. The invention further provides an air purifier.