An example electronic device may include a display including a main display area and at least one expansion display area expandable from the main display area; and a processor operatively coupled to the display. The processor is configured to, while the electronic device is in a slide-in state, display, on the main display area, a first screen corresponding to an application executed in the slide-in state; based on a portion of the expansion display area being slid out, generate a second screen to be displayed on the main display area and a portion of the slid-out expansion display area; generate a slide effect screen and display the same on at least a portion of the slid-out expansion display area, at least at the same time as the generation of the second screen; and based on the generation of the second screen being completed, remove the display of the slide effect screen and display the second screen on the main display area and the slid-out expansion display area.