To provide a paper conveying device capable of preventing a disk to be detected from being cut off or damaged even if a helical gear is used.

This paper conveying device comprises a conveying roller shaft 27 rotatably supported by a frame 21, a motor 41 for rotatingly driving the conveying roller shaft 27 through the helical gear 34 fitted to the conveying roller shaft 27, the disk 35 to be inspected fitted to the conveying roller shaft 27, and a sensor body 37 fitted to the frame 21 and detecting the rotation of the disk 35 to be detected. The paper conveying device further comprises a coil spring 40 for pressing the conveying roller shaft 27 to the reference end 30c of the frame 21 by biasing it in the thrust direction. The biasing force of the coil spring 40 is larger than a thrust force by the helical gear 34. The coil spring 40 is disposed coaxially with the conveying roller shaft 27. The conveying roller shaft 27 extends through the coil spring 40.

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