The present invention provides a method for manufacturing organic acid by high-efficiency fermentation, which comprises the steps of continuous culture of organic acid bacteria and collection of organic acid produced from the culture employing a cell-recycle multiple-stage continuous fermentor with serially connected fermentors, each of which comprises a fermentor containing a ferment container, temperature controller, stirrer, and pH controller; pumps for efflux-circulation of media from the fermentor; and, cell separator for separation and circulation of media from the pumps. According to the present method, the high-concentration lactic acid of 90 g/L can be produced with the high productivity of 50 g/L/h, which can reduce the facility cost and production cost in the bulk manufacturing process. In addition, the present invention can be effectively applied to the production of other organic acids such as acetic acid, formic acid, citric acid, malic acid, maleic acid, fumaric acid, and succinic acid, which show the end-product inhibition.