To provide an air filter unit, in which miniaturization, space reduction and improved treatment efficiency are attained in a simple constitution.

A storage part 20 stores multiple air filter units 2 with main faces of a filter medium arranged roughly vertical to the flow direction of air during use raised and juxtaposed in order horizontally. Treatment parts 30, 40, 50 are arranged at one end side of the direction juxtaposing the air filter units 2 in the storage part 20 in order, in line with respect to the air filter units 2 in order of treatment. Transporting part 70 is arranged along the storage part 20 and treatment parts 30, 40, 50, releasably holds the air filter units 2, and moves them horizontally and vertically along the storage part 20 and treatment parts 30, 40, 50.