1. A method of combining effective images in an electronic device having a plurality of cameras, the method comprising: in response to a photographing signal, temporarily storing images successively photographed through a first camera; selecting a first image which satisfies a predetermined classification reference from the images successively photographed through the first camera; and combining a second image photographed through a second camera with the first image, wherein the predetermined classification reference is a numerical value of a shooting composition, wherein the shooting composition is a numerical value of a matching degree between a position of a user's face and a position of a subject in a shooting composition divided into halves or thirds by comparing the positions.