Indole Acetic Acid (IAA) is one type of hormone that can stimulate plant growth. IAA hormone is able to accelerate plant growth, especially in the early stages of growth. IAA hormones are not always found in plants, one of which can be found in microorganisms. Rhizobacteria group have the ability to produce IAA hormones. This study aims to determine whether the IAA produced by Serratia marcescens strain MBC1 is able to accelerate the germination process of soybean seeds (Glycine max L.). The results of the Analysis of Variance (ANOVA) giving the production of IAA Serratia marcescens strain MBC1 of 8.31 ppm and 9.35 ppm to soybean seed germination significantly increased root length and stem length. The increase in germination from the administration of IAA Serratia marcescens MBC1 was still smaller than the positive control using synthetic IAA with a concentration of 8 ppm which was able to significantly increase soybean germination.