This paper explained results of the observed tsunami characteristics caused by the 2004 Tokaido-off Earthquake. Offshore tsunami profiles were obtained from the Nationwide Ocean Wave information network for Ports and HArbourS (NOWPHAS) wave observation network and newly installed Muroto-off GPS buoy. Offshore tsunami data of the NOWPHAS seabed installed acoustic and pressure wave gauges nationwide network data and the GPS buoy data were compared with the coastal tide stations data.
　It was concluded that NOWPHAS network seabed installed gauges and the GPS Buoy successfully observed tsunami profiles with good precision at the event. GPS buoy of 100m deep observed the first tsunami wave 10 minutes earlier than the coastal tide station, which indicated that GPS buoy will be useful for rapid coastal evacuation and tsunami disaster reduction. Tsunami amplification characteristics from offshore GPS buoy observation points to coastal tide gauge points were also clarified at the Muroto area, by conducting tsunami profile wave-to-wave analysis and frequency spectrum analysis.