To provide protective structure of a water-barrier sheet in a waste disposal site in which the water-barrier sheet is easily avoided from being damage even when a heavy machinery is run or circled in the upper part to spread and level waste and also the water-barrier sheet is set rapidly and easily without using protective sand.

The protective structure 10 protects a water-barrier sheet 11 spread and set on the base ground 20 of a waste disposal site and is constituted by lengthwise, crosswise and successively providing and arranging many protective blocks 13, which have strength undamaged by the upper load caused by a heavy machinery and waste 31, on the upper face of the water-barrier sheet 11. Further, the protective blocks 13 are equipped with recessed grooves 14 or notches 15 forming drainage flow paths 16 between the protective blocks 13 and the water-barrier sheet 11 by allowing the blocks 13 to communicate with one another in the case of lengthwise, crosswise and successively providing and arranging them 13 on the base.