A bar code reader comprising a photodetecting section for receiving light reflected from bar codes scanned with scanning light and for outputting an electric signal corresponding to the intensity of light received, a demodulating section for demodulating the electric signal and for generating demodulation bar code data, a storage section for storing demodulation bar code data, a timing section which starts measuring a first time when the demodulation bar code data is stored in the storage section, an area judging section for judging which area, out of first and second areas to which the scanned range scanned with scanning light is divided, is scanned to generate the modulation bar code data demodulated by the demodulating section, a judging section for judging whether or not demodulated bar code data demodulated prior to demodulation bar code data and stored in the storage section coincides with the demodulation bar codes, and a judging section for judging that the demodulation bar code data is improper when the bar code data is generated by scanning the first area, when the judging section judges that the bar code data coincides with the modulation bar code data, and when the first time has elapsed, whereby the same bar codes are prevented from being read doubly.