PURPOSE: To perform the correction of the contents of a storage device in an easy method and to erase ineffective character strings for an electronic typewriter, by re-storing information in the storage device for the correction.

CONSTITUTION: The whole system of a character string storage device is controlled by a microprocessor MPU10, and the control program for it is stored in an ROM11 as control codes. In an RAM 12 connected between the MPU10 and ROM11, the conditions of the system or generally used stored information is stored, and in the character string storage device 13, the starting address of a character string and the character string represented in character codes are stored. Further, a buffer 14 for character string transfer and a memory address decoder 15 are connected to a data bus DB, an address bus AB, and a system control bus SCB. To correct the information in the device 13, an address from the MPU10 is decoded by a decoder 14 to control the RAM12, buffer 15, etc., thus performing the correction easily.