From the middle of the twentieth century, microalgae have been exploited as a candidate biomass source of food and other products. One such candidate source is the fast-proliferating microalga Euglena gracilis. The commercial cultivation of E. gracilis began in 2007, after the success of its outdoor mass cultivation and improvement of the harvesting and drying methods suitable for Euglena cells. The commercialization of Euglena production is based on the strategy of "5Fs of Biomass," which refers to the development and production of commercial products including food, fiber, feed, fertilizer, and fuel from biomass." Although room for improvement remains in the productivity of Euglena biomass, the product with the highest value-food-is already profitable. By enhancing the productivity of its biomass, other Euglena products, including fiber, feed, fertilizer, and fuel, can be commercialized. Breeding and recombinant DNA technology studies are being conducted to accomplish more extensive application of Euglena. In addition, the search for a better place for outdoor mass cultivation of Euglena is ongoing.