YM-47522, a novel antibiotic, was isolated from the culture broth of Bacillus sp. YL-03709B. The antibiotic was purified by centrifugal partition chromatography and ODS column chromatography. It exhibited potent in vitro antifungal activity especially against Rhodotorula acuta and Pichia angusta (MIC: 0.05 and 0.75 microgram/ml, respectively). It also showed moderate or weak antifungal activity against Candida albicans and Cryptococcus neoformans (MIC: 25 and 6.25 micrograms/ml, respectively), whereas it was inactive against filamentous fungi and bacteria.