We experimented to see if the tolerance of Agaricus bisporus to Pseudomonas sp. causing the bacterial brown blotch disease which is causing great damage in the button mushroom cultivation was inherited. There was no correlation between mycelial growth rate and mushroom tolerance to pathogens at each temperature. In the mycelial stage, the strains tolerance to Pseudomonas sp. were not as strong as those of their parents, but they were generally stronger or more tolerance than those of weaker strain (ASI1321). In fruiting body, tolerance was decreased compared to mycelial. In fruiting body, later generations of two strains had similar tolerance, unlike strong or weak tolerance of parental generation. Therefore, browning of fruit body is thought to be caused not only by tolerance but also by various other factors. Especially, the future generation of the strains which were tolerance to Pseudomonas sp. were very weak in the mycelial stage, indicating that the tolerance of the parental generation was inherited to the later generations. The damage of each pathogen was different in mycelium and fruiting body. P. tolaasii caused higher browning than P. agarici in fruit body. P. reactans did not have a significant effect on the mycelium but affected the browning of the fruit bodies. P. agarici had higher mycelial growth inhibitory ability than fruiting body.