One of the superior commodities that is needed by almost everyone from various circles of society, namely purple eggplant solanum melongena L) Eggplant is not just a vegetable that is only processed as a family meal, but also contains quite high nutrition. Ultisol soil is a potential soil that can be used as agricultural land, but has a low level of nutrient cages. Soil fertility problems need to get a solution through the provision of organic material in the form of rice straw compost. Rice straw compost is a fertilizer that has the highest nutrient content compared to other organic fertilizers. The purpose of this study was to determine the effect of rice straw compost fertilizer on purple eggplant plant bacilli and to obtain the best dose of rice straw compost for eggplant plant yields. In this study there were 20 polybags of purple eggplant plant samples using a single factor RAL consisting of 4 levels of treatment, namely k0 (control) k1 (10% rice straw compost 90%, soil) k2 (30% rice straw compost 70% soil) and k3 (50 % rice straw compost 50% soil, each treatment was repeated five times so that 20 experimental units were obtained with the parameters observed were the number and weight of purple eggplant fruit at the first harvest.The results of this study showed that the application of rice straw compost fertilizer significantly affected the number of fruit and had a very significant effect on fruit weight of purple eggplant at the first harvest. Even though the use of 30% giraffe and 10% of the soil composition gave the same effect, for more efficient use of giraffe was enough with 30% giraffe 10% of the soil. So the best K2 treatment for the first harvest of purple eggplant