Communication-identifier-assigned image data is transmitted via a set channel using the same as a communication identifier set for each image transmitter and a channel set in transmission. Then, a receiver which has received a plurality of image data items stores the received image data items, communication identifiers, and channels in such a manner that the received image data items are related to the communication identifiers and channels. Thumbnailed images in each image data item are displayed on one screen. When an image is selected from the thumbnailed images, an image transmitter that has transmitted the image is determined on the basis of the communication identifier and channel related to the selected image and is connected exclusively to the receiver. Images acquired from this time on are enlarged and displayed chronologically on a display section. The image transmitter and receiver constitute a wireless communication system.