The Iriomote cat, Prionailurus bengalensis iriomotensis, is a small felid endemic to Iriomote-jima Island (284 km²) in the Ryukyu Archipelago, Japan. According to its topography, Iriomote-jima Island can be divided into a coastal-lowland area (CLA) and inner-mountainous area (IMA). Since 1983 the home range and spacing pattern of the Iriomote cat population have been investigated by radio-tracking and camera-traps mostly in the CLA. Few ecological studies on the cat inhabiting the IMA have been conducted because of difficulty of surveys. Since direct observations of the Iriomote cat are difficult in the wild and tracks, scats and footprints of the cat are also difficult to find in IMA, we attempted to detect inhabitation of the cat by camera-trapping in IMA. A survey was conducted in both the CLA and IMA from 2003 to 2011. We fixed a control area in the CLA where the number of the cats was known by other surveys, and set camera-traps. Asides from the control area, we also set 10 continuous camera-traps in 18 areas for one year each. We attempted to estimate population density of the Iriomote cat by comparison of photographing rate of the cat among areas. Additionally, we visualized the border between CLA and IMA, using GIS slope angle data. We compared the CLA and IMA densities of the Iriomote cat and other animals detected by camera-traps.