A concentrated solution (liquid concentrate) for preparing a surface conditioner, a surface conditioner (a treatment solution for preparing a surface), which have the excellent stability of dispersion and a method of a surface conditioning using this surface conditioner are provided. The concentrated solution for preparing a surface conditioner contains zinc phosphate particles and has a pH of 3 to 12. The zinc phosphate particles are of D.sub.50 3 .mu.m or less and the concentrated solution for preparing a surface conditioner contains a laminar clay mineral.