A feasibility study for the evaluation of the Secchi Disk Depth (SDD) by SGLI in Lake Nakaumi which is located in Shimane Prefecture, Japan, was conducted by using the in-situ spectral reflectance data collected in August 2005. As a result, the following conclusions were obtained. (1) The characteristics of spectral reflectance in the lake and their relationship to the band positions of the SGLI sensor were qualitatively understood. (2) Relatively high correlations were obtained between "VN4, VN5, VN6, and VN7" bands of SGLI and SDD. (3)The SDD in the lake can be estimated from the multiple regression method using SGLI four bands (VN4, VN5, VN6, and VN7) with the RMS error of about 0.2 m.