Soybean has got broad planting area in the world and is first oil plant at the vegetable oil production. Density, viscosity and oxidation stability are characteristic of methyl ester which using as a alternative fuel in internal combustion engines. In this study, soybean oil has chosen that is one of the most available sources as raw material for biofuel production in this sector. Soybean methyl ester has derived with transesterification from this raw material. Soybean methyl ester has at certain volume to 6 different samples, have examinated changes of physical properties of fuel by means of expose directly to sunlight certain times. One of the samples has chosed as a reference fuel and has storaged different ambient and changes have determined graphically according to others samples has expose to sunlight. Thanks to this study don’t have to expose to sunlight principle have again lay stress on which one of the pay attention subject at storage of biofuels