Large rotational motions excited by earthquakes are recorded during an earthquake swarm of March, 1997, offshore Ito in Izu peninsula, Japan. The largest rotational velocity recorded at KAW is 2.6¿10-2 rad/s around the north-south axis during an earthquake of magnitude 5.2 at 14:09 (GMT) on March 3. The rotational motions around the vertical axis excited by the largest event is 3.3¿10-3 rad/s. Considering a spatial variation of slip velocity which directly relates to excitation of a rotational motion, we apply a simple point source model to the largest event and succeed in explaining the observed rotational motion around the vertical axis. ¿ 1998 American Geophysical Union