Microorganisms such as alga are able to uptake toxic and heavy metal ions. After Cd(Ⅱ) was preconcentrated on the carbon paste electrode constructed by incorporating alga (Anabaena), it was determined with differential pulse anodic stripping voltammetry. A well-defined oxidation peak of Cd(Ⅱ) was obtained at - 0.75 V vs. SCE. We investigated the optimum conditions using the peak, which are the effect of the amount of alga, pH, ionic strength, temperature, and preconcentration time on the preconcentration of Cd(Ⅱ) and that of the reduction time and potential on the reduction of Cd(Ⅱ) preconcentrated. Calibration curve for the determination of Cd(Ⅱ) was linear over the range of $1.0{ imes}10^6;M;to;8.0{ imes}10^6$;M (R=0.9978) and the detection limit was $5.0{ imes}10^{-7}$;M</TEX>. The relative standard deviation was 3.1% (n=6) for $7.0{ imes}10^{-6};M Cd(Ⅱ). In regeneration of the electrode surface with 0.1 M HCl, the response was reproducible continuously by 10 times.