The present invention provides a method for manufacturing highly-concentrated polyglutamic acid by culturing an aerobic micro-organism of Bascillus sp. with the additional supply of saccharides. The method for manufacturing polyglutamic acid comprises a step of culturing Bascillus sp. in a fed-batch or batch culture while supplying saccharides to the culture. Since the method for manufacturing highly-concentrated polyglutamic acid can be applicable to the industrial scale fermentation, mass production of polyglutamic acid can be feasible in a cost-efficient way.