A binding device includes a switch to manipulate, based on a push of the switch, a crimping and binding operation in which media to be bound are crimp-bound, the crimping and binding operation performed when the switch is turned on, the crimping and binding operation stopped when the switch is turned off, and a mode selector to choose one of a first operation mode in which the switch is turned on while the switch is being pushed and the switch is turned off when the switch is released and a second operation mode in which the switch is kept being turned on or the switch is kept being turned off when the switch is pushed and then released and the switch is switched between a state in which the switch is turned on and a state in which the switch is turned off every time the switch is pushed.