Several examples are presented which seismic quiescence appeared in a wide area around the foci of intraplate earthquakes before their occurrence. A noteworthy feature is that the quiescence area extends along tectonic zones over more than several times of the focal region of the main shock. This phenomenon suggests that stress in a wide area along tectonic zones changes before the occurrence of major intraplate earthquake. We consider that the stress change is a manifestation of a significant physical process leading to earthquake occurrence. An apparently puzzling fact which earthquake precursors are sometimes observed at distant places from the focal region in the specific direction may be explained by such stress change. Further, it is expected that the precursory seismic quiescence provides us with a promising clue to the short-term prediction of intraplate earthquake.
