To provide a bookbinding device that saves an installation space and adopts the pasting process.

In this bookbinding device 10B, a stack tray 28 loads the pasted paper. A paste transfer mechanism 13B applies the paste to the paper loaded entirely on the stack tray 28. A pressing unit presses the upper surface of top paper of all the pieces of paper loaded on the stack tray 28 and contact bonds the paste-transferred paper to the paper stacked on the former. The paste transfer mechanism 13B avoids the pasting procedure to the paper to be loaded last on the stack tray 28 of all the other pieces of paper which constitute one copy of booklet. The pressing unit presses the upper surface of the top paper of the booklet located at the top level of the booklet tray 28 and avoids the pressing procedure to the upper surface of the top paper of the other booklet.