A polyurethane resin is composed of a polyol component, a polyisocyanate component and optionally, a chain extender component. At least a portion of the polyol component or chain extender component is a siloxane polyol component represented by the following formula (1) and/or formula (2): ##STR1## wherein R means an alkyl group, R' denotes a hydrogen atom or C.sub.1-5 alkyl group, k, l and m stand for 1-250, 0-5 and 0-50 respectively, and n is an integer of 1-3 in the formula (1) and an integer of 2-3 in the formula (2). A thermal recording material containing the polyurethane resin as a heat-resistant layer is also disclosed.