Objectives of this study were to propose an optimal fertilization method of Chlorella and to evaluate its effects on growth of green pepper. Chlorella fusca strain was propagated and used in the experiment. As for treatment, drenching method (DM), foliar fertilization (FF), drench and foliar fertilization combination (DM + FF), and untreated control (CO) were used. Plant height of green pepper was higher in the CO treatment than in chlorella fertilized treatments. Chlorella fertilization inhibited stem growth of green pepper. Chlorophyll contents of green pepper leaves were higher in the DM + FF treatment. Yields were the higher in DM and DM + FF treatments than in other treatments. Vitamin C content was the highest in the DM + FF treatment. These results showed that Chlorella fertilization could increase the growth, yield, and bioactive substance content of green pepper. The Chlorella fertilization method could be applied to other crops. By applying this technology to the farmer, it is possible to increase income and supply healthy and safe high-quality agricultural products to consumers.