A concentrator chip which could detect a variety of heavy-metal ions was fabricated. To improve the detection sensitivity, a droplet of a sample solution was concentrated evaporatively using a super-hydrophobic surface formed with polytetrafluoroethylene (PTFE) beads. The system consists of a working electrode at the center, surrounded by an Ag/AgCl reference electrode. Square-wave anodic stripping voltammetry was conducted using concentrator chips with different working electrode materials. A significant increase in peak height was observed as the sensitive area decreased and the volume of the droplet increased. When a 5-μl droplet was used, the detection limit for lead, cadmium, and arsenic ions was 1 ppb.