In a communication system, an image forming apparatus sends an address of a receiving section to an external device. The external device receives a selection of image data through plural thumbnails displayed on a display section, and wirelessly sends the selected image data to the image forming apparatus with the address. The image forming apparatus receives the selected image data sent with the address by the external device, and prints an image based on the selected image data. The image forming apparatus accepts a selection indicating whether a communication between the external device and the image forming apparatus is performed by a first communication system method or a second communication system method. The image forming apparatus performs sending and/or receiving the image data with the address by the first communication system method when the first communication system method is selected, and performs sending and/or receiving the image data with the address by the second communication system method when the second communication system method is selected.