the present invention provides a printer comprising : an image read unit which has a slot corresponding to a type of recording medium , and reads an image from a recording medium inserted into the slot ; an image obtaining unit which obtains an image showing a shape of the recording medium ; an identifying unit which identifies the type of recording medium based on the image showing the shape of the recording medium ; a guide unit which guides to and displays a slot corresponding to the identified type ; and a print unit which prints the image read from the recording medium , in order to prevent wrong insertion of the recording medium .