PURPOSE: To improve filling workability and a deaeration characteristic by forming a filling chute into a freely retractable inside/outside double tube, transforming the filling chute, which is inserted into an opening part of a storage bag, from an extended condition to a shrunk condition according to an advance in filling of a powder material, and carrying out exhaustion via a dust collecting duct.

CONSTITUTION: In filling work of a powder material, a hanging handle 90 arranged in a flexible container bag 70 is hooked on a flexible container hanging metal fitting 100 suspended via a hanging rod 105, in which a load cell measuring device 104 is provided. Then, a filling chute 60 is inserted into an opening part 70-1 of the flexible container bag 70, and a retractable cylinder 81 is extended so that an outside tube 60-1 of the filling chute 60 is extended most from an inside tube 60-2. Under this condition, filling is started and a filling amount is measured by the load cell measuring device 104, and when the filling amount reaches the predetermined amount, two-step gates of a two-step controlling gate 83 are closed sequently while the retractable cylinder 81 is shrunk, so that air inside the flexible container bag 70 is exhausted via the clearance between the inside tube 60-2 and the outside tube 60-1 and a dust collecting duct 60-3.