This study was performed to select adequate plant materials for developing a natural α-glucosidase inhibitor by analyzing α-glucosidase inhibition activity in fronds and rhizomes of three Dryopteridaceae species: Cyrtomium fortunei, Polystichum polyblepharum, and P. lepidocaulon. The highest α-glucosidase inhibitor obtained from frond of P. lepidocaulon (4.16μg·mL-1), and rhizome of C. fortunei (1.84μg·mL-1), showed much higher inhibition activity than acarbose (1413.70μg·mL-1). The biomass required to inhibit α-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, α-glucosidase inhibition activity was the highest in water fraction of C. fortunei (20.2μg·mL-1), and n-butanol fraction of P. lepidocaulon (9.33μg·mL-1) and P. polyblepharum (5.10μg·mL-1). In rhizome, it was the highest in n-butanol fractions of C. fortunei (19.76μg·mL-1) and P. polyblepharum (4.47μg·mL-1), and ethylacetate fraction of P. lepidocaulon (5.46μg·mL-1). The frond biomass required for 50% α-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 α-glucosidase inhibition activity with small biomass, which might have high value as materials for economical anti-diabetic medication.