There are several kinds of nutritious materials in Spirulina maximum, and beta-carotene is one of the most important materials. Because beta-carotene is of low polarity, for purification it was extracted with the mixture of acetone and methanol in the ratio of 7:2 (V/V), then saponified, and extracted with petroleum ether, purified with column packed with neutral Al2O3. Its content was determined by reversed-phase HPLC. This method is accurate and the results are reproducible. The average recovery was 96.8%.