According to a printer of the present invention, the displaying unit creates a print image of the image received by the receiving unit and displays a preview of the print image when the loss detecting unit detects the lost part of the image, and the displaying unit creates a print image of an image obtained as a result of the trimming and displays a preview of the print image when the trimming unit trims the image, and the printing unit prints an image obtained as a result of the trimming by the trimming unit. Consequently, if a user failed in communicating an image as the user did not set an external communication terminal to an appropriate place and the image has been lost, the user can display a preview of the image by removing the lost part by trimming and display the lost part by a preview, check the trimmed image and print it.