To provide a light fire fighting ladder at a low cost by suppressing vibration while ensuring strength.

The ladder comprises a ladder assembly body of a plurality of steps composition. The ladder assembly body is constituted by successively fitting each ladder in an expansible manner. The ladder consists of an upper master aggregate, a lower master aggregate, a diagonal aggregate connecting both of them, a cross rib connecting both lower master frames to each other and a cross rib diagonal aggregate connecting both cross ribs. Each member is connected by welding. The lower master aggregate is equipped with square shaped pipes 2 and 3 and a folded plate material 4 held between both of them. The height of the folded plate material 4 is higher than heights of the square shaped pipes 2 and 3, and it is projected in the upper direction of the square shaped pipes 2 and 3. The folded plate material 4 is so placed that it can not be projected downward of the square shaped pipes 2 and 3.