In the course of our screening program for new antibacterial compounds, a strain A24566 isolated from a lichen collected at Jyogasaki, Shizuoka prefecture, Japan, was found to produce a potent antibiotic. This compound, BE-24566B (1), was isolated from the mycelial cake of cultural broth, and was shown to have a unique structure. BE-24566B possesses potent antibacterial activity against Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). The strain A24566 was identified as Streptomyces violaceusniger based on characteristics such as L,L-diaminopimelic acid in whole cell hydrolysate, spiral spore chains with rugose surface, and carbon source utilization. BE-24566B was purified via methanol extraction, ethyl acetate partitioning, silica gel column chromatography, and Sephadex LH-20 column chromatography, yielding 209.6 mg. Its physico-chemical properties (pale yellow powder, molecular formula C27H24O7) and structure were determined using UV, IR, NMR (1H, 13C, HMBC, COSY), HR FAB-MS, and derivative preparation (dimethyl ether). Antibacterial activity was tested by twofold serial dilution, showing MIC values of 1.56–3.13 μg/ml against Gram-positive bacteria including MRSA. Single intraperitoneal administration of 100 mg/kg to CDF1 female mice caused no death. This paper describes the strain, production, isolation, physico-chemical properties, structure elucidation, and biological activity of this new antibiotic, which may serve as a new lead for antibacterial agents.