To provide a bag type dust collector in which the whole equipment does not enlarge even in the bag type dust collector provided with a line-off function.

The bag type dust collector has a constitution that a compressed air jet nozzle for cleaning 9 connected to a cleaning air supply tube 8 is arranged opposing to the opening end 7a of a bag filter 7 filtering dust-containing air such that the bag filter 7 is cleaned by the compressed air jetted out of the compressed air jet nozzle 9. The bag type dust collector comprises a lid member 21 covering the opening end 7a of the bag filter 7 at a downward position and at the same time, forming an opening 21a allowing the passage of the compressed air jetted out of the compressed air jet nozzle 9, a cylindrical airflow blocking member 22 blocking a space between the compressed air jet nozzle 9 and the lid member 21 from the circumference, and a movement mechanism 30 to move the lid member 21 between a rising position and the downward position.