The present invention relates to a bar code copy prevention method and a device therefor. In detail, when a terminal provides a one-time bar code for an electronic payment, the one-time bar code is provided to a user in a state which a bar code scanner cannot recognize by changing the one-time bar code for the electronic payment, and when the bar code scanner exposes a light source in order to recognize the one-time bar code for the electronic payment, a light source recognition module installed in the terminal recognizes the light source of the bar code scanner, a payment may be performed by recovering an original bar code which the bar code scanner can recognize from the changed bar code, and thus an illegal use of the bar code may be prevented since the payment is not performed using the captured bar code.
