During the 2011 off the Pacific coast of Tohoku Earthquake, the earthquake early warning system operated by East Japan Railway Company controlled the Shinkansen trains through information from its seismic stations before large shakings hit the line. By analyzing the event history of the system recorded in its monitoring PCs, it was confirmed that the system first detected the seismic motion at 14:46:38.9 (JST) based on the data of the Kinkazan seismic station located closest to the epicenter, and issued the first control signal to trains between Shiroishi-Zaoh station and Kitakami station of the Tohoku Shinkansen line at 14:47:02.9 through the excess of acceleration threshold of the Kinkazan seismic station. The signal was issued 12-22 seconds earlier than the time SI value exceeding 18 cm/s along the line, which is the required value to stop trains based on company rules. After issuing the first control signal, other seismic stations began issuing signals through the excess of acceleration threshold almost sequentially according to certain delays caused by wave propagation from the hypocenter. Eventually, 27 trains (19 of them were running) along the line were safely controlled.
 In this paper, after summarizing the configuration of the earthquake early warning system of East Japan Railway Company and the warning logics adopted for the system, the system performance during the 2011 off the Pacific coast of Tohoku Earthquake is evaluated and discussed in detail.