Background: Lead is one of the four metals that has most complication on human health. Although there has been no known vital effect for it, lead can be collected in living systems to be toxic. Lead enters the environment by different approaches. One of the methods for heavy metals impurity detection in environment is cellular biosensor. Cellular biosensor is cell containing one reporting gene under the control of promoter that is sensitive to an element (such as heavy metals). One of the important operons in Ralstonia bacterium resistance to heavy metals is pbr. This research was done to design biosensor containing pbr promoter with Luciferase reporting gene in E.coli (DH5α) as host. Materials and Methods: The pbr promoter sequence with pbrR as regulator gene in 634 nucleotide size was synthesized and Luciferase reporting gene in pGL3 plasmid was located under this promoter. Then the recombinant plasmid was transferred to E.coli (DH5α). These bacteria were able to detect the lead in the environment and were used to detect different concentrations of lead in medium. Results: The least concentration of lead that can significantly express Luciferase reporting gene was 1µM and the most concentration of it was 100µM. It seemed that the concentration above 100µM caused decrease in reporting gene expression through toxic effects on biosensor survival. Conclusion: The results indicated that this biosensor can detect 1-100 µMol concentration of the heavy metal "Lead" in aqueous solutions.