This research was conducted to investigate changes in isoflavone contents and sprouting characteristics of germinated soybeans [Glycine max.] under light condition. The relative wet weight of soybeans increased as germination progressed, and it reached $291.1{pm}14.3%$ at 60 h after beginning of sprouting. On the other hand, relative dry weight slowly decreased as germination progressed. The length of sprouting rapidly increased as germination progressed. The sprouting rate sharply increased from 12 h to 48 h and reached $96.4{pm}2.5%$ at 60 h after sprouting. In terms of color, L value did not change until 24 h after the beginning of germination, but it rapidly increased from 24 h to 36 h and did not change thereafter. The a value rapidly increased at 24 h after the beginning of germination and decreased thereafter. The b value rapidly increased at early and last stages and reached $9.0{pm}0.7$ at 60 h after the beginning of sprouting. Total isoflavone reached a maximum level at 12 h after the beginning of germination and consistently decreased thereafter. Among isoflavone compounds, m-genistin had the highest content followed by daidzin and m-daidzin.