Abstract: In a thermal recording sheet including a substrate having thereon a thermal color developing layer containing colorless or pale colored basic achromatic dye and an organic color developer, the thermal color developing layer contains aluminium hydroxide and a urea-formaldehyde resin pigment. The thermal recording sheet is small in abrasion of the recording head and adherence of depositions to the head even after long-run recording, and friction staining in unrecorded portion due to the recording head and change in gloss in unrecorded portion during recording are small.

Abstract: A thermal recording medium wherein ultraviolet absorbent is included in undercoat layer and/or in thermal sensitive color developing layer, ultraviolet isolator consisted of calcined particle which is flaky pigment whose refractive index is 1.5 to 1.6 and whose surface is coated with insoluble cerium compound and amorphous silica is included in thermal sensitive color developing layer and/or in protective layer, and fluorescent dye is included in protective layer.