1. A multitask management method of an electronic device, comprising: receiving a first user input while a first execution screen of an application is displayed on a touchscreen of the electronic device; displaying, on the touchscreen, a stack of partially overlaid visual elements in response to the first user input, each visual element corresponding to an application that is running in the electronic device and including a task termination item for terminating an application corresponding to the visual element; receiving a second user input for selecting a visual element from the stack of partially overlaid visual elements; displaying, on the touchscreen, an execution screen of an application corresponding to the selected visual element; and in response to receiving a third user input on a task termination item of a visual element in the stack, terminating an application corresponding to the visual element the task termination item on which the third input is received and removing the visual element corresponding to the terminated application from the stack, wherein the stack of partially overlaid visual elements comprises visual elements corresponding to each of all applications that are running and a visual element representing the first execution screen of the application is placed on top of the stack, and wherein an interval between consecutive visual elements in the stack is adjusted based on the number of visual elements displayed on the touchscreen.