PURPOSE: To provide a misrecognized character detecting system capable of automatically checking a character recognizing result in an automatic drawing input device for optically reading out a document, a drawing, or the like including characters and graphics and recognizing each character.

CONSTITUTION: Characters are previously registered in each character string to form (S1) a correct character string data base 10. A character recognizing result is compared (S4) with each character string stored in the data base 10. When the recognized result character string exists in the data base 10, the character string is erased from the data base 10. When the character string is not included in the data base 10, or when similar contents are included in the data base but are not a correct interpretation, a correct interpretation is selected from the data base 10 and the character string is successively corrected.