This study was performed to select adequate plant materials for developing a natural ${alpha}$-glucosidase inhibitor by analyzing ${alpha}$-glucosidase inhibition activity in fronds and rhizomes of three Dryopteridaceae species: Cyrtomium fortunei, Polystichum polyblepharum, and P. lepidocaulon. The highest ${alpha}$-glucosidase inhibitor obtained from frond of P. lepidocaulon ($4.16{mu}g{cdot}mL^{-1}$), and rhizome of C. fortunei ($1.84{mu}g{cdot}mL^{-1}$), showed much higher inhibition activity than acarbose ($1413.70{mu}g{cdot}mL^{-1}$). The biomass required to inhibit ${alpha}$-glucosidase by 50% was 0.04 ~ 0.35mg for frond and 0.03 ~ 0.10mg for rhizome, and P. lepidocaulon required the least amount of fronds and P. lepidocaulon the least rhizomes. In frond, ${alpha}$-glucosidase inhibition activity was the highest in water fraction of C. fortunei ($20.2{mu}g{cdot}mL^{-1}$), and n-butanol fraction of P. lepidocaulon ($9.33{mu}g{cdot}mL^{-1}$) and P. polyblepharum ($5.10{mu}g{cdot}mL^{-1}$). In rhizome, it was the highest in n-butanol fractions of C. fortunei ($19.76{mu}g{cdot}mL^{-1}$) and P. polyblepharum ($4.47{mu}g{cdot}mL^{-1}$), and ethylacetate fraction of P. lepidocaulon ($5.46{mu}g{cdot}mL^{-1}$). The frond biomass required for 50% ${alpha}$-glucosidase inhibition was the lowest in the water fraction of C. fortunei (1.43mg), and n-butanol fractions of P. lepidocaulon (1.10mg) and P. polyblepharum (0.66mg). The required biomass of rhizome was the lowest in the water fraction of C. fortunei (1.59mg), and n-hexane fractions of P. lepidocaulon (0.04mg) and P. polyblepharum (0.15mg). The result of this study suggested that the three Dryopteridaceae species had high ${alpha}$-glucosidase inhibition activity with small biomass, which might have high value as materials for economical anti-diabetic medication.