To allow a necessary and sufficient amount of glue for gluing a cover 51 to be applied on the back of a bookblock W while reducing the application amount of the glue by precisely smoothing the back of the bookblock W.

A bookblock processing device includes: a rotary head 10 rotated and driven at a high speed; a disk-like grindstone tool 13 mounted coaxially on an upper surface of the rotary head 10 and using an upper surface as a grindstone surface; and a rotary cutter (blade tool) 11 mounted coaxially on the upper surface of the rotary head 10 and having a cutting edge 11a arranged circularly on an outer circumference of the grindstone tool 13. For the back of a bookblock moving parallel to the grindstone surface of the grindstone tool 13, the rotary cutter 11 performs the cutting, and the grindstone tool performs the grinding.