There was a degraded ecosystem and an affected decreasing nekton and microbenthos at River Pelus. So far, no publication of macrobenthos is available. The research purpose was to map species richness and longitudinal distribution of macrobenthos. The survey method was taken with stratified random sampling in eight stations and five replicates from May to July 2018. The result showed ten species of macrobenthos. All species belonged to class Malacostraca (four species) and Gastropoda (six species). Of the four species collected in all replicates, Macrobrachium oenone categorized as an indicator species that only lived in Station II because there were a boulder substrate and good water quality. In the same class, M. pilimanus, Parathelpusa bogoriensis, and P. convexa were in all stations except station V because there was a sand substrate and poor water quality. In station V, there were only two species of gastropod, Melanoides riquerti and Pomacea canaliculata that could live. In general, there were a cosmopolitan species that could live in all substrates and water quality such asM. riquerti. For a longitudinal distribution map, there was a unique tendency of decreasing species richness numbers due to the river weir.