Plant diseases are a serious threat to food production. This unique volume provides the fundamental knowledge and practical use of B.subtilis as a promising biocontrol agent. In order to replace chemical pesticides, one possibility is microbial pesticides using safe microbes. Bacillus subtilis is one of several candidates. Screening of the bacterium, the application of plant tests, clarification of its suppressive mechanism to plant pathogens and engineering aspects of suppressive peptides production are presented here. The author illustrates how B. subtilis is far more advantageous than, for example, Pseudomonas in biocontrol and can be considered as an useful candidate.