Expansive soil is a type of soil that has a high potential for swelling and shrinkage. As a tropical country, Indonesia has two distinct seasons: the rainy and dry seasons. This condition affects expanded clay. During the dry season, the soil will shrink and crack due to reduced water, while in the rainy season, the soil will swell due to the increased water content in the soil. This study aims to determine the effect of Bio Grouting or MICP using Bacillus subtilis bacteria on changes in the mechanical properties of expansive soils. Expansive soil stabilization was carried out by adding bacterial solutions ranging from 3%, 4.5%, and 6%, where the bacterial cultures used were three days and six days of culture. Based on the study's results, it was found that the MICP method using the bacterium Bacillus subtilis could increase the value of unconfined compression strength. The optimum unconfined compression strength value was obtained in soil samples with the addition of 4.5% bacterial culture solution for six days with a curing period of 28 days of 16.46 kg/cm2 or 51 times higher than the unconfined compression strength value of soil without stabilization.