Abstract
　The horizontal wind field of the typhoon, T9119, was analyzed using the surface wind data at the meteorological stations in Japan. In this analysis, observed wind speeds were corrected according to the surface roughness of each station. The 10-min mean maximum wind speed attained to 40-50 m/s over flat surface in western Japan and the coastal area of Sea of Japan. The calculated wind field from the empirical formula compares favorably with the observation, and also suggests that wind speeds around Japan are enhanced by fast moving velocity of the typhoon nearly 100 km/h.
　The wind storm of T9119 is as strong as those of the strongest typhoons which landed in Japan for recent 40 years. The gust factor in typhoon area slightly increases during recent 40 years, which result is mainly attributed to the increase of the surface roughness z0 around each meteorological station.

【キーワード】：台風，最大風速，突風率，地表面粗度
Key words: typhoon, maximum wind speed, gust factor, surface roughness

*東北大学理学部地球物理学教室
Geophysical Institute, Faculty of Science, Tohoku University