Article history:IJMM 2019; 12(6): 409-418 Background and Aims: Marine Actinomycetes are gram-positive bacteria that sometimes are free, saprophytic or plant and animal-associated, including marine sponges. More than 75% of antibiotics and antimicrobial compounds are produced by actinomycetes. In recent years, due to the need for new drugs, marine microorganisms have been considered as new sources of potential production of significant metabolites. The purpose of this study is isolation and identification of marine sponge-associated Actinomycete and investigation of its antibacterial activity. Materials and Methods:The Actinomycete was isolated from the marine Sponge collected from the depths of coastal waters in Bushehr and screened for antibacterial activity on pathogenic microorganisms of Escherichia coli، Bacillus cereus، Klebsiella spp.، Salmonella spp. and Proteus spp. using a Disk Diffusion Method. For molecular identification, genomic DNA was first extracted from isolate and then, the16S rDNA gene was amplified by PCR and Sequenced. The results were analyzed using bioinformatic programs, Bioedit and MEGA6. Results:In this study, based on phylogeny studies, it was determined that the isolate belonged to thegenus Streptomyces, and biochemical studies showed that all tests except catalase and gram were negative; antibacterial activity study showed significant activity against three pathogenic bacteria, E. coli, Bacillus cereus and Salmonella spp. It was more active against Salmonella spp. (around 16mm inhibition zone diameter). Conclusions:The results showed that depths of the Bushehr coastal waters have marine sponge associated actinomycetes, which are a source of secondary metabolites with biological activity.