This study investigated the hypoglycemic effect of the Padina arborescens extract in STZ-induced diabetic mice. Freeze-dried Padina arborescens were extracted with 80% methanol and concentrated for use in this study. The hypoglycemic effect was determined by inhibitory activities against ${alpha}$-glucosidase and ${alpha}$-amylase as well as the alleviation of postprandial blood glucose level. Padina arborescens extracts showed higher inhibitory activities than acarbose, a positive control against ${alpha}$-glucosidase and ${alpha}$-amylase. The $IC_{50}$ values of Padina arborescens extracts against ${alpha}$-glucosidase and ${alpha}$-amylase were 0.26 and 0.23 mg/mL, respectively, which evidenced as more effective than observed with acarbose. The increase of postprandial blood glucose levels were significantly suppressed in the Padina arborescens extract administered group than the control group in the streptozotocin induced diabetic mice. Furthermore, the area under the curve (AUC) was significantly lowered via Padina arborescens extract administration in diabetic mice (p 0.05). These results indicated that the Padina arborescens extract might be used as an inhibitor of ${alpha}$-glucosidase and ${alpha}$-amylase and delay absorption of dietary carbohydrates.