To provide the paper dust-collecting device capable of collecting and removing most of the paper dust generated from the paper exit of a drier and from a winding reel.

This paper dust-collecting device of a paper-drying installation is used for collecting paper dust generated between the paper exit of a drier 2 equipped with a creping doctor knife 3 and a cleaning doctor knife 4 and a winding reel 7 for winding paper delivered from the paper exit. Therein, a hood 10 capable of covering the paper exit and the winding reel, capable of being extended from the base end on the side of the paper exit to the side of the winding reel and further capable of opening or closing the opening 11 on the side of the winding reel with a lifting or lowering curtain 12 is disposed, and the base end of the hood is allowed to communicate with a paper dust- removing device 32 such as a scrubber with a duct 30 through a suction fan 31.