An image forming apparatus that causes a user's will concerning which of a communication speed and power saving efficiency is given priority to be reflected on determination of a power saving mode. In shifting the apparatus to a power saving mode, a first setting inhibits disconnection of a communication link and a second setting indicates changing communication speed to a lower speed. One of the first and second settings is made according to a user's instruction. In the first setting, the apparatus is shifted to a first power saving mode. In the second setting, the apparatus is shifted to a second power saving mode. When the apparatus is shifted to the first power saving mode, the communication link is not disconnected. When the apparatus is shifted to the second power saving mode, the communication speed of the apparatus is changed to the lower speed.