1. A user terminal apparatus comprising: a camera; a display; at least one processor; and at least one memory configured to store one or more computer programs configured to be executed by the at least one processor, the one or more computer programs including instructions for the at least one processor to: generate an image of a user by capturing the user using the camera, control the display to display the generated image of the user, detect an eye of the user from the generated image, control the display to display a guide image in a position of the generated image in which the detected eye of the user is located, and in response to a difference between a size of an iris included in the detected eye of the user and a size of the guide image being within a preset range, perform iris recognition.