In the course of a screening program for new antibiotics, we found a new manumycin group antibiotic named nisamycin (1) in the culture broth of the strain K106. This strain was isolated from the soil sample collected in Sakai city, Osaka prefecture, Japan and identified as a genus Streptomyces sp. In this paper, the fermentation, isolation, structure and biological properties of 1 are reported (Fig. 1).