To provide a stone-fall protection device which can efficiently absorb and disperse a great energy of a falling stone.

A main rope 18 is extended between two posts 14 that are placed on a slope with a lateral spacing between them. A rectangular-like net 22 is stretched on the main rope 18 with suspension ropes 20 on the valley-side slope. The posts 14 are kept in the upright position by support ropes 16 that are extended between the mountain-side slope and the posts 14. The net 22 is attached with cross ropes 34, which are installed extending across the net 22 with a designated slack with both ends of each of them being anchored to the slope at the outside of both sides of the net 22. The cross rope 34 is fitted with buffer means 36 near its both ends. An energy of a falling stone S is absorbed by the entire deformation of the net 22 and the buffer means 36 fitted on the cross rope 34, and at the same time transferred and dispersed in the direction to the slope outside the net 22 by a total of 5 lengths of the cross ropes 34.