|Rock tunnels suffered severe damage from recent large earthquakes in Japan, despite the empirical knowledge that tunnels tolerate earthquakes better than surface structures. Seismic design for rock tunnels have therefore become a fascinating subject for many tunnel engineers. However, even basic behavior of tunnel has not been fully understood due to lack of actual seismic data. In thisstudy, dynamic data was measured at an actual tunnel and the seismic motion during earthquakes was evaluated through instrumental seismic intensity, acceleration, velocity and strain of the tunnellining. The acquired results are: Seismic intensity at the tunnel is smaller than that on the ground surface. Seismic intensity at the tunnel is almost the same as that in the ground with distance of 20m from the tunnel. Strain of the tunnel lining was only 4x10-6 at maximum during the measurement, though maximum instrumental seismic intensity was 2 at the tunnel.