The northward expansion of I. pertinax (Selys, 1854) in the region of eastern Shikoku and western Kinki Districts was investigated by reviewing a number of former papers. Some ecological factors enabling the species to expand northward were considered, based on observations which have been made in and near Kobe since its first discovery in 1987. This expansion started from southern Kochi about 50 years ago and the yearly mean air temperature has risen by about 1.0 to 1.7°C during the last 95 years in this region. The rise of air temperature coincides with both the temporal and spatial expansions.