The use of sunscreen is a way to protect the skin from the danger of UV exposure. Nowadays, there are a lot of sunscreens based on chemical (synthetic organic) on the market, such as ovobenzone, oxybenzone, otisalate which have proved as toxic chemicals for the skin. The researches related to the use of natural ingredients as active agent for sunscreen are continuously increasing, one of them is the microalgae. Microalgae Spirulina plantesis is cyanobateria which has naturally absorbed UV compounds in its cells, namely flavonoid. Flavonoid has the potential to be used as active sunscreen's ingredient because of its ability to absorb maximum wavelength in the range of UV rays, as well as increase the SPF value. In this research, flavonoid is varied in the range of 1-10% w/w and the ratio of olive oil:candelilla wax were varied, which were 10:1 and 5:1 with the composition's range of wax is 35-40% w/w to obtain both optimal cream stability and SPF values from sunscreen cream preparations. The results show that the total flavonoid compound in the dried and fresh basis sample of microalgae were 22.10 mg/g extract and 10.91 mg/g extract respectively. The best composition of sunscreen on this research was sunscreen with 7% (w/w) microalgae extract and the ratio between olive oil: candelilla wax was 35:7, because this formulation gives good SPF value (29.06) which is categorized as ultra-SPF and has the good stability score (17.33 from 20). Therefore, the sunscreen from microalgae extract which contains flavonoid are safe to use, because the total microbes were still below the required total microbial of SNI and did not irritate the skin.