Provided is a filter bag for use in a dust collector which increases a filter area greatly even with a simple structure, and which makes size of the dust collector compact, to thereby reduce an installation area of the dust collector, and uniformly distributing an air pressure to thereby increase a dust removal effect as well as to enable a worker to easily manufacture the dust collector regardless of a quality of a material to thus provide a wide application range. The filter bag includes: a cylindrical filter cloth (32) which is supported by a filter cage (31); and a venturi tube (35) which is combined with the upper end of the filter cage 31, and forms an air supply path so that pressurized air is supplied to the inside of the filter cloth (32), wherein the filter cloth (32) comprises an cylindrical outer filter cloth (33) which is provided in the outside of the filter cage (31), and an inner filter cloth (34) whose lower portion is combined with the inner circumference of the inner circumferential surface at the lower end of the outer filter cloth (33) so as to be opened and which is extended toward the venturi tube (35).