1. A character reading apparatus for processing an input data sheet including character data, comprising: reading means for scanning the input data sheet and for photoelectrically converting the scanned input data sheet to image data; image storing means for storing the image data; character recognizing means for comparing the image data stored in said image storing means with pre-stored known image data and determining whether results of the comparison exceed a predetermined level, wherein said image data having the comparison result exceeding the predetermined level are output as outputting recognized character data, and said image data having the comparison result failing to meet the predetermined level are output as for detecting and outputting a reject character; display means for displaying the recognized character data, an indicator mark in place of the reject character, and the reject character at predetermined positions on said display means, respectively, the reject character being displayed in a form of the image data stored in the image storing means; display control means for displaying the reject character at a different predetermined position on the display means when the reject character overlaps the character data containing the reject character; and reject character modifying means for modifying the reject character to a correct character.