An image forming apparatus is provided. The apparatus includes an image forming unit which performs an image forming job, a communication unit which forms a wireless network according to a predetermined wireless communication standard, a control unit which, if at least one terminal device is connected to the communication unit through the wireless network, determines whether it is required to perform warming-up of the image forming apparatus and performs warming-up of the image forming apparatus, and a storage unit which stores information regarding a connection status of the terminal device. Accordingly, stand-by time for performing an image forming job may be reduced.