PURPOSE: To make any printing blank possible to be printed on an electronic instrument with a printer consisting of an electronic instrument body and a printing blank holder by a method the blank holder is made detachable.

CONSTITUTION: When an electronic instrument body 1 is set to a blank holder 24, a contact switch 44 is turned on and when it is removed from the holder, the switch is turned off. For either case, first, a motor 9 is driven by operation of a key 2, a type wheel 6 rotates and selection of a type is made. When the type 7 arrives at a printing position, a coil 18 is charged with electricity and therefore, a selection click 12, is inserted into a groove of a positioning member 11. If the above said processes are made over all columns, the rotation of the motor stops when the switch 44 is off. Therefore, after printing is carried out manually a restart switch 53 is pressed. When the switch is on, automatic printing is carried out. After printing is finished, the click 12 is separated from the member 11, the type wheel returns to the original position and the paper is fed.