A tooth surface treatment material and method to eliminate a smear layer, to deliver an inorganic component of a tooth structure in a dental cavity to the tooth structure to make a glass ionomer cement firmly adhere particularly to a dentin which includes an aqueous solution containing 2.about.30% by weight of a water-soluble calcium salt and an acid which does not react with the calcium salt by 1/2 or less of the weight of the calcium salt and having a pH of 2 or less and an aqueous solution containing a water-soluble phosphate other than a calcium salt, or an aqueous solution containing 2.about.30% by weight of a water-soluble calcium salt and an aqueous solution containing 2.about.30% by weight of a water-soluble phosphate other than a calcium salt and an acid which does not react with the phosphate by 1/2 or less of the weight of the phosphate and having a pH of 2 or less, the acid-containing aqueous solution being first applied, and the other solution being subsequently applied onto the teeth surface.