1. An image photographing device photographing an image through a front camera and a rear camera, the image photographing device comprising: a display unit; a feature extraction unit extracting facial features from an image of a user's face displayed on a preview screen through the rear camera; a structure extraction unit extracting the structure of the user's face by using the extracted facial features; an expression extraction unit extracting the expression of the user by using the extracted facial features if the extracted structure of the face matches a standard facial structure; and a notification unit outputting a photographing notification signal if the extracted expression of the user matches a standard facial expression.