Dye transfer type thermal printing sheet

The present invention provides dye transfer type thermal printing sheet comprising a base sheet, a dye-containing layer formed on the base sheet and a dye-permeable layer which is formed on the dye-containing layer and comprises at least one water dispersible polysiloxane graft polymer which is obtainable by polymerizing (B) 0.05 to 10 % by weight of a polymerizable silane compound, (C) 1 to 30 % by weight of an unsaturated organic acid and (D) 40 to 97.95 % by weight of a monomer which is copolymerizable with the silane compound (B) and the unsaturated organic acid (C) in the presence of (A) 1 to 20 % by weight of a polysiloxane having terminal hydroxyl groups (provided that the total of the components (A), (B), (C) and (D) is 100 % by weight) in an organic solvent except an alcohol or at least one salt of said graft polymer with a base, which has good storage stability, generates images with improve weather durability and prevents great decrease of print density as increase of the number of printing times.