PURPOSE: To provide an antiseismic device which eliminates any possibility of OA equipment from falling off a top plate due to earthquake motion or acting on any other external force by a post-attached fixing means even in the OA equipment just mounted on the top plate.

CONSTITUTION: An antiseismic device is constituted of a pair of anchor members (A), (A) which are detachably fixed to the edge part of a top plate TB and a variable-length belt member (B) whose both ends are locked to the anchor member (A), intermediate part is mounted on the table TB, and which is wound around the DA equipment.