FILTER UNIT AND PROJECTION-TYPE PICTURE DISPLAYING DEVICE

PROBLEM TO BE SOLVED: To provide a filter unit which automates the cleaning of an air filter without increasing an air filter accommodation space and is easily disposed of without re-scattering dust removed from the air filter.SOLUTION: The filter unit 3 includes an air filter (specifically, a first air filter 40) which captures dust in sucked air; and a cleaning part (self-propelled cleaning part 60) which automatically cleans the air filter. The cleaning part has a rotary brush 64 which scrapes dust away which adheres to the air filter; and a dust box 65 which is provided with a dust intake 65A, which takes dust adhered to the rotary brush 64, on the rotary brush side in a longitudinal direction which is parallel to the direction of the rotary center shaft of the rotary brush 64. Furthermore, the dust box 65 is removably mounted on the filter unit 3.