The invention discloses a bar code attaching machine which comprises two label attaching machines (1) and an overturning machine (2) for overturning a contracted battery for 180 degrees, wherein the overturning machine (2) is positioned between the two label attaching machines (1). Compared with the prior art, the invention has the advantages that after one surface of the contracted battery is attached with a bar code by the previous label attaching machine, then the contracted battery is automatically overturned for 180 degrees by the overturning machine, and directly enters the latter labelattaching machine so that the other surface of the contracted battery is attached with the bar code to finish the entire process, so that manual operation of a worker is unnecessary, and the worker only puts the contracted battery at the entrance of the previous label attaching machine, therefore, the labor intensity of the worker is relatively low, and the production efficiency is generally fourtimes of that of the prior art; meanwhile, the worker can directly butt the entrance of the previous label attaching machine with the exit of a battery packing machine, thus, the automation degree ishigher; a worker can watch at least four bar code attaching machines disclosed by the invention, so the production efficiency is at least four times of that of the prior art; and the number of workers and wage payment are reduced.