PURPOSE: To wash a number of bag filters at a time without requiring manual operation by spraying washing liquids from a washing liquid spraying unit to perform washing after a bag filter has been supported by a supporter member and then circulating dry air by means of a blower to achieve drying.

CONSTITUTION: There are provided, in a washing tank 1, bag filter supporter members 8, 9, washing liquid spraying units 2, 3 disposed respectively in the upper and lower sections of the tank, and a blower, while a blower port and a discharge air port are formed near the blower. After bag filters are supported by the supporter members 8, 9, various kinds of washing liquids are sprayed from the spraying units 2, 3 to perform washing and then dry air is circulated by means of the lower to achieve drying. As a result, manual operation is not required and a number of bag filters can be washed at a time and further chemical washing can be performed.