As a new dehydration method, purple sweet potato (Ipomoea batatas) slices were dehydrated with maltodextrin (MD) with concentrations of 20, 40, 60, and 80% (w/w). The moisture content of the purple sweet potatoes decreased with an increasing MD concentration. The rehydration ratio of the MD-treated samples was better than those of freeze dried or hot-air dried samples, and the color and total phenolic content of the dehydrated samples were well maintained for the MD-treated one. The anthocyanins in the exudates were obtained after the MD treatment of purple sweet potatoes, and the stability was examined for use as a food colorant. These results suggest that purple sweet potatoes can be dehydrated effectively with MD, and that anthocyanins in the exudates are applicable as a natural food colorant.