To obtain a composition which can improve resistance to abrasion and bending of a porous layer containing a pigment of a low refractive index without being influenced by a preserving time until printing, and also gives the layer a moisture keeping character which ensures a speed of discoloration and a duration of wet state when written by water.

This composition is not influenced by preserving the time until printing by using an acrylic resin and a wetting agent, or the like as components of a binder resin, can secure resistance to abrasion and bending by using a plasticizer and a surface active agent, can improve, without damaging concealability in a dried state and transparency in a wetted state, concealability of the porous layer by using an aluminium silicate as the pigment having the low refractive index and whiteness by joint use of a magnesium carbonate. Further, use of a wetting agent makes a time of keeping a state of a changed color longer and joint use of an acrylic-vinyl acetate copolymer improves water permeability of a painted film and can accelerate a speed of changing color by wetting.