Abstract. Microalgae are potential biomass to be used as a biofuel raw material. The microalgae used are high in fat and carbohydrates as a biofuel candidate. The environment and species of microalgae determine the growth and content of microalgae. The purpose of this research is to utilize waste know as tofu for the growth of microalgae cultivation and raw materials for biodiesel. The method used is the cultivation of microalgae to the concentration of tofu waste 1ml / 1L saltwater as a medium to grow microalgae, then harvesting performed, followed by drying, smoothing and flour. Microalgae extracted with soxletase method to determine its crude oil content, GC-MS used to determine the free fatty acids and production of biodiesel, the biodiesel characterization isan initial study. The results suggest that oil content is 8.6% / dry weight microalgae for tofu cultivation and 2.5% walnefertilizer. Fatty acid composition of microalgae Tetraselmissparepalmitic acid (C16: 0), stearic acid (C18: 0) and oleic acid (C18: 1), characterization of biodiesel produced to the acid number of 4.14 mg KOH / g, viscosity of 2, 6 g / cm3 and the density 2,6cSt.