PURPOSE: To perform a printing action for a running test, the adjustment of a printing mechanism part, and the like by a method wherein when character font data and a control program are not loaded to an internal memory from an external storage device at the throw-in of a power source, a control program of an internal storage means is read, and the character font data thereof is used for printing.

CONSTITUTION: When a control means 5 detects that character font data and/or a control program cannot read from an external storage device 2 at the throw-in of a power source, it reads a control program stored in an internal storage means 3 to operate. A character pattern of a character font stored in the internal storage means 3 is read and issued to a printing part 6 to be printed. Namely, using the character pattern of the character font stored in the internal storage means 3, in accordance with the instruction of the control program stored in the internal storage means 3, the control means 5 can conduct a printing action for a running test, the adjustment of the printing part 6, and the like.