Vascular epiphytes are plants that grow on trees without contact to the soil. Although forests in southeast Asian tropics have rich epiphyte flora, their within-forest distribution has not sufficiently accumulated. Here, we investigated the number of species and individuals and substrate types (bare bark or humus) of epiphytes growing on 7 species and 47 matured individuals of dipterocarp trees in a primary lowland rainforest in Borneo. We recorded a total of 82 species and 2,147 individuals of epiphytes. Epiphyte species richness and abundance were significantly higher in two Dipterocarpus species than in the others. Species composition of epiphytes was significantly varied among host species, it was especially pronounced in the species of Dryobalanops and Shorea. Among the epiphyte individuals investigated, approximately 50% of individuals occurred on bare bark, and the other occurred on humus-accumulated habitats. Some epiphyte species were found on the humus that was trapped by the other epiphyte species. Our results suggest that primary forests with a variety of tree species are essential for the maintaining of epiphyte diversity, and the establishment of an epiphyte individual can be influenced not only by host species but also by other epiphyte individuals that co-occur on a tree.