Social insect colonies remain perpetually in contact with various microorganisms ranging from pathogenic to symbiotic, where defense against pathogens is often provided by symbiotic microorganisms. Here we report that actinobacteria in the nest material made of feces protect colonies from entomopathogen in the damp wood termite Hodotermopsis sjostedti. We found no mycelial growth of naturally-occurring fungi from termite carcasses buried in the feces, while carcasses in autoclaved feces were covered with many mycelia. The actinomycete Streptomyces costaricanus isolated from the feces strongly suppressed the growth of entomopathogenic bacteria Bacillus thuringiensis and fungi Metarhizium anisopliae and Beauberia bassiana. Our metagenomic analyses revealed that antibiotic-producing Streptomyces species were abundant in the nest material but not detected from the hindgut of workers. Our results suggested that termites protect their colonies from pathogens not only by their own antimicrobial substances but also by antibiotic-producing bacteria living in their nest material.