To provide a protective device preventing the adhesion of oils onto a sandy beach, rocks and tetrapods even when oils flowed out on the sea are floated on the surface of the sea and thrown up on a coastline by waves.

In the protective device for the coastline, a weight 3 is installed on one side of hydrophilic cloch 1 and a plurality of cables 4 on the other side while baggy sections 1a filled with air are mounted on the hydrophilic cloth 1 so as to be spread from a folded state. Fasteners connecting mutual hydrophilic cloth 1 are set up to both sides or either one side, on which the weight 3 and the cables 4 of the hydrophilic cloth 1 are fitted, or sections excepting the cables 4 are housed in a container capable of being opened and closed as required.