PURPOSE: To correct a character string inputted in wrong shift mode without performing keying operation again, by providing a shift correction key and a storage means for a cursor position when a shift correction is indicated and another cursor position when correct shift mode is reindicated.

CONSTITUTION: A device which has a keyboard 1 and displays codes of an input character string after code conversion 3 at a display part 5 after storing them in a character storage part 4 is provided with a shift correction key 11, and registers 121 and 122 for storing a cursor position when a correction of a character string inputted in wrong shift mode is indicated and another cursor position when correct shift mode is reindicated with the key 2. After the correction key 11 is pressed, correct shift mode is set with the key 2, and then the cursor positions stored in said registers are referred to detect a character string to be corrected in the storage part 4, thereby performing conversion to the correct shift mode.