An image forming apparatus including: a staple unit including a staple mechanism configured to drive a staple through a bundle of sheets and a driving source configured to make the staple mechanism operate; a data input portion (3b, 6) for receiving print data used for printing; a print unit configured to execute a print job based on the print data; a power supply configured to supply electric power to the staple unit; and a control unit configured to make the power supply supply electric power to the staple unit at least until a standby time elapses after completion of a print job, to start to count time that elapses after completion of a print job, to make the power supply stop supply of electric power to the staple unit when the elapsed time equals the standby time, to predict whether or not a printout of an executed print job requires stapling, to set, when it is predicted that no stapling is required, the standby time to a first time, to set, when it is predicted that stapling is required, the standby time to a second time that is longer than the first time, the control unit not being connected to the staple unit via a communication signal line, and not recognizing whether or not the staple unit is present, the image forming apparatus further comprising: an operation panel on which operations are received, wherein the operation panel includes hardware keys and a touch panel, characterized in that the control unit is further configured to reset the elapsed time and start to count the elapsed time from zero, when the hardware keys are operated or when the touch panel is touched. a staple unit including a staple mechanism configured to drive a staple through a bundle of sheets and a driving source configured to make the staple mechanism operate; a data input portion (3b, 6) for receiving print data used for printing; a print unit configured to execute a print job based on the print data; a power supply configured to supply electric power to the staple unit; and a control unit configured to make the power supply supply electric power to the staple unit at least until a standby time elapses after completion of a print job, to start to count time that elapses after completion of a print job, to make the power supply stop supply of electric power to the staple unit when the elapsed time equals the standby time, to predict whether or not a printout of an executed print job requires stapling, to set, when it is predicted that no stapling is required, the standby time to a first time, to set, when it is predicted that stapling is required, the standby time to a second time that is longer than the first time, to make the power supply supply electric power to the staple unit at least until a standby time elapses after completion of a print job, to start to count time that elapses after completion of a print job, to make the power supply stop supply of electric power to the staple unit when the elapsed time equals the standby time, to predict whether or not a printout of an executed print job requires stapling, to set, when it is predicted that no stapling is required, the standby time to a first time, to set, when it is predicted that stapling is required, the standby time to a second time that is longer than the first time, the control unit not being connected to the staple unit via a communication signal line, and not recognizing whether or not the staple unit is present, the image forming apparatus further comprising: an operation panel on which operations are received, wherein the operation panel includes hardware keys and a touch panel, characterized in that the control unit is further configured to reset the elapsed time and start to count the elapsed time from zero, when the hardware keys are operated or when the touch panel is touched. an operation panel on which operations are received, wherein the operation panel includes hardware keys and a touch panel, characterized in that the control unit is further configured to reset the elapsed time and start to count the elapsed time from zero, when the hardware keys are operated or when the touch panel is touched.