To provide a protector which secures the safety of operation space with reliability similar or superior to that provided by structures of the prior art although the protector does not have a horizontal brace piece nor a column near its center.

A cushioning material layer 13 is provided on the roof 12 of a protector 1 in such a way as to have a certain thickness. The kinetic energy of an object falling from the top of a tunnel is absorbed by the cushioning material layer 13 and the distance over which the object falls before colliding against the protector 1, i.e., the kinetic energy of the falling object, is smaller than before. Therefore, although the protector does not have a column 11 near its center and no horizontal brace piece is used at the connection between the column 11 and the roof 20, the protector can secure the safety of operation space with reliability similar or superior to that provided by structures of the prior art.