BAR CODE READER WRITER

PURPOSE:To improve the operation efficiency and save the space at the time of bar code system installation by recording bar code data on a label by reacting and color-changing by a light beam having different characteristics from read use light from the bar code reader writer, and equipping a single equipment body with both a reading and a writing function. CONSTITUTION:The bar code label 107 coated with a marking material which changes its color by reacting to only the light beam having a certain characteristic and a light emission source 104 which emits the light beam having the characteristics are provided, and the bar code label 107 is scanned with the light beam. Further, this reader writer is provided with a means 106 which performs mutual conversion between a data format that an external computer 109 can recognize and the bar cope data, a means 105 which recognizes a difference in the reflection factor of the projected light beam between the ground color of the label and at least one color, and a means 101 which judges whether or not the read data are normal consequently, the bar code can be not only read, but also recorded.