A reverse flow preventing device arranged in a flow path of fluid formed by a fan and an electronic apparatus equipped with the same. The reverse flow preventing device has a frame, a plurality of support shafts arranged about the center of the frame and mounted on the frame, and a plurality of pivotable plate members supported by the support shafts. The plate members can move between the first position (reverse flow preventing position) in which they lie in a substantially single plane and the second position (normal operating position) in which they move. The support shafts and the plate members are arranged substantially concentrically or radially.