Research on the diversity of molluscs has been carried out in the mangrove forest of Nusa Lembongan. The purpose of this study was to determine the species of mollusks that interact in the mangrove habitat, to support a scientific interpretation of the existence of mollusks in the mangrove forest of Nusa Lembongan. The research was conducted in seven mangrove forest sites, from April to June 2022 using the quadratic method. At each research site determined five sampling squares. Identification of mollusk species based on morphological characters (shape, size, shell texture and shell color). The abundance of each species was calculated based on the number of individuals per unit area (m2). The diversity of molluscs was calculated using the Shanon-Wiener diversity index. The results showed that 24 species were found in the mangrove forest of Nusa Lembongan, 19 species from the gastropod class and 5 species from the bivalves class. Several species that were quite dominant were the mangrove periwinkle Littoria scabra, with a density of 28.4 individuals/5 m2, sulcate swamp Terebralia sulcata, a density of 10.2 individuals/5m2, mud creeper Cerithidea obtusa, with a density of 7.2 individuals/5m2. The diversity of mollusks species in the mangrove area of Nusa Lembongan is included in the moderate category with a diversity index of 2.79 and an evenness index of 0.88. Based on the diversity index, it shows that the condition of mangroves in Nusa Lembongan is still relatively good or steady. The diversity of mollusks, the abundance of each species, the unique characteristics of each species, and the presence of mollusks in the substrate or mangrove vegetation are scientific interpretations and attractive attractions for eco-friendly mangrove tours.