Protein tyrosine phosphatase 1B (PTP1B) acts as a negative regulator of insulin signaling, and selective inhibition of PTP1B has served as a potential drug target for the treatment of type 2 diabetes. As part of our searching for PTP1B inhibitors from natural products, the extracts of marine microorganisms were screened for the inhibitory effects on the activity of protein tyrosine phosphatase 1B (PTP1B). Among the tested 304 extracts, 29 extracts exhibited inhibition rate ranging 40.1 - 83.6 % against PTP1B at the concentration level of $30{mu}g/mL$.