To provide a relatively lightweight wall adhering material comprising a non-woven fabric or a water-resistant paper, having a specific coating weight as a substrate and provided thereon a specific amount of a porous layer, a water-discoloring wall adhering material which has excellent convenience at the time of production and use, promptly forms clear image to perceive, is difficult to fall down when adhered to a wall, and has high commercial value, and a water-discoloring wall adhering material set using the same. A water-discoloring wall adhering material 1 comprising a non-woven fabric 2 or a water-resistant paper, having a coating weight of from 40 to 150 g/m.sup.2 and provided on the surface thereof a porous layer 3 in an amount of from 5 to 50 g/m.sup.2, the porous layer comprising a binder resin and a low-refractive-index pigment dispersed in the binder resin and firmly fixed thereto, and the water-discoloring wall adhering material 1 having a gross weight of from 50 to 200 g/m.sup.2, and a water-discoloring wall adhering material set comprising the water-discoloring wall adhering material and a wall fixture or a tool for water adhesion, or a water-discoloring wall adhering material set comprising the water-discoloring wall adhering material, a wall fixture and a tool for water adhesion.