Bean bug, Riptortus pedestris (Hemiptera: Alydidae) is an agriculturally serious pest in East Asian countries. Chemical pesticides have been contributed to the management of the pest, but nowadays insect resistance limits the use of chemical pesticides, thus alternatively new pesticides with different mode of actions such as entomopathogenic fungi are considered. Herein entomopathogenic Beauveria bassiana JEF isolates were collected, identified and assayed against bean bugs in laboratory conditions. Some isolates showed >80% virulence by contact-exposure and spray methods. The Agrobacterium tumefaciens-mediated transformation of B. bassiana JEF-007 generated random transformants and some mutants showed reduced virulence against Tenebrio molitor (Coleoptera: Tenebrionidae) larvae and R. pedestris nymph. Compared to the wild-type, the two transformants showed remarkably different morphology, conidial production, and thermotolerance. To figure out pathogenicity-related genes, thermal asymmetric interlaced (TAIL) PCR of the random transformants was performed and possibly some virulence-related genes were predicted. This work can be a strong platform for the functional genetics of bean bug-pathogenic B. bassiana.