-(1→3)-D-glucans with -(1→6)-glycosidic linked branches are known to be immune activation agents and are incorporated in anti-cancer drugs and health-promoting supplements. -Glucan concentration was 9.2 g/L in a 200-L pilot scale fermentor using mutant strain Aureobasidium pullulans M-2, which was from an imperfect fungal strain belonging to A. pullulans M-1. The culture broth of A. pullulans M-2 had a faint yellow color, whereas that of the wild-type had an intense dark green color caused by the accumulation of melanin-like pigments. -Glucan produced by A. pullulans M-2 was identified as a polysaccharide of D-glucose monomers linked by -(1→3, 1→6)-glycosidic bonds through GC/MS and NMR analysis. When a conventional medium was used in the culture of A. pullulans M-2 in a 3-L jar fermentor, -glucan concentration was 1.4-fold that produced by the wild-type. However, when medium optimized by statistical experimental design was used with dissolved oxygen at 10%, the -glucan concentration was 9.9 g/L with yield of 0.52 (g -glucan/g consumed sucrose), which was 2.9-fold that of the wild-type. This level of productivity was reproduced when the fermentation was scaled up 200-L. The industrial production of high -glucan without melanin-like pigments is highly expected as a health-promoting supplement or functional food.