To provide a bookbinding device which efficiently performs a bookbinding operation by making it possible to control time required for holding a paper bundle after applying an adhesive according to circumstances under which the device is used.

The bookbinding device comprises the following components: a clamping part 7 for holding a paper bundle 6; an application unit 3 for applying a thermally molten adhesive 8 to the back of the paper bundle 6 held by the clamping part 7; a timer circuit 67 for measuring elapsing time after the completion of applying the adhesive 8 to the back of the paper bundle by the application unit 3; a temperature sensor 66 for detecting the ambient temperature of the bookbinding device 1; a control part 65 for setting the time required for holding the paper bundle in order to keep the holding state of the clamping part 7 after the completion of applying the adhesive 8 under the temperature detected by the temperature sensor 66 as temperature conditions for the use environments; and a signal output circuit 68 for outputting a signal when the elapsing time measured by the timer circuit 67 has reached the limits of time required for holding the paper bundle.