Horizontal and vertical distribution of chlorophyll-a concentration(Chl-a) in Lake Shinji was estimated using Landsat TM data, vertical Chl-a(μg/l), relative illuminance(%), water temperature ( ^゜C), salinity(psu) data simultaneously acquired on 3 March 1998 at about 10:30 a.m. As a result, the following things were found out: 1) Chl-a along the south shore side in Lake Shinji was lower than that along the north shore side. 2) Vertical Chl-a in Lake Shinji gradually increased to lower layer.3) When the depths of the euphotic layers are assumed as the depths at which illuminance is 1% of the surface level, the average ± SD of Chl-a standing stock in Lake Shinji was 49.4 ± 13.5mg/m^2.