To induce the enhanced mutants of dinitroaniline herbicide pendimethalin degrading bacterium, Bacillus sp. MS202 was irradiated with gamma radiation at the dose of $LD_{99}$ (3.35 kGy). Three enhanced mutants (MS202m7, MS202m14, MS202m18) were isolated from the candidates by the generation - isolation method. Clear zone formation and the GC analysis confirmed that the degrading activity of each enhanced mutant (MS202m7, MS202m14, MS202m18), the formation of pendimethalin metabolite, increased by $11\%,;45\%,;and;32\%$ than a wild type, respectively. It suggested that these mutants induced by gamma radiation could be useful for the application of pesticide degradation.