Purpose: This study aimed to investigate the composition and biological activities of common and tartary buckwheat during germination, and to compare them. Methods: The effect of the germination time on vitamin C, γ-amino butyric acid (GABA), rutin and quercetin, total polyphenol and flavonoid contents were determined. Results: The vitamin C content reached a maximum on the fifth germination day. As the time of germination increased, the GABA content of the tartary and common buckwheat increased from 2.49 μ g/100 g and 9.59 μg/100 g to 25.17 μg/100 g and 57.84 μg/100 g, respectively. D-chiro-inositol (DCI) is a bioactive compound that serves as a mediator of insulin action. DCI in common and tartary buckwheat was found to be 129.65, 76.31 mg/100 g, respectively, with a significant increase in the DCI content as germination progressed. During germination, the total polyphenol and flavonoid contents tended to increase as germination time increased. The ABTS and DPPH radical scavenging activities in germinated samples increased with germination time and were caused by an increase in their anti-oxidative activities. Moreover, the results showed that the vitamin C and GABA content of the common buckwheat samples were higher than those of the tartary buckwheat samples with the changing trends of total polyphenols and flavonoids opposite to each other. Conclusion: It may be concluded that germinated buckwheat can find a unique use as a natural health product due to the presence of bioactive compounds with health benefits.