To efficiently perform operation for improving a character recognition rate when character recognition is carried out by an image input/output device.

The image input/output device which receives image data including characters in an image and transfers them to an image recording and reproducing device, is equipped with a character recognizing means 110 which recognizes the characters included in the received image data, a discrimination means 166 which discriminates whether the character recognition result of the character recognizing means is success or failure, and a protecting means 168 which protects the image data as the object of character recognition when the decision means discriminated that the character recognition of the character recognizing means is failure.