The growth medium is one aspect that determines the production of algal biomass as a raw material for biofuels. Cultivation of Mastigocladus HS-46 in NPK medium with the addition of bean sprout extract has been done. In a previous study, Mastigocladus HS-46 could be grown in NPK medium. This study was aimed to determine biomass production of Mastigocladus HS-46 in NPK medium by adding varying concentrations of bean sprout extract. The growth medium used in this study consisted of BBM as control and NPK with the addition of bean sprout extract with concentrations of 0%, 2%, and 4%. Biomass was cultured in a flat photobioreactor system and incubated in the greenhouse at the Biology Department, Universitas Indonesia. Observation result showed that NPK medium with the addition of 2% bean sprout extract produced the most biomass, weighing 77 mg/mL with lipid content of 61%.