Abstract: A method and device for avoiding defective elements in a thermal printer having a thermal head on which a greater number of heating elements than the number of bits in printing data are linearly continuously arranged, and an output register associated with the bits in the heating elements and adapted to deliver printing data for one line to the heating elements, wherein when some of the heating elements become defective, the printing data is shifted a suitable number either to the right or to the left so as to correspond to the non-printing bits in the printing data and is then transferred to the output register. According to the invention, in the case of, e.g., bar code printing, even if some of the heating elements become defective, printing can be continued without any trouble, so that great improvements in productivity and quality control can be achieved.