This work demonstrates the properties of calcium-fortified potato starch prepared by immersion in natural mineral water containing an extremely high level of calcium (468 ppm) and its food application. The calcium content of the fortified potato starch produced by use of the original mineral water was as high as 813 ppm, while calcium content of the control potato starch was 99 ppm. Rapid visco-analyzer data revealed that the calcium-fortified potato starch had a markedly lower peak viscosity and breakdown and a higher peak viscosity temperature than the control potato starch. Furthermore, calcium fortification caused a significant decrease in starch swelling power. Pound cakes made from the calcium-fortified potato starch and wheat flour blends tended to have a higher specific volume and sensory score of appearance than those made from the control potato starch and wheat flour blends. These findings suggest that the use of calcium-fortified potato starch is critical for making pound cakes with good quality in appearance.