<p>A heat-sensitive recording material which has a high recording density, ensures recorded images of high quality and allows printing on the reverse side. A base paper for the recording material is subjected to multilayer paper making by means of a paper machine having a multilayer head box. The surface layer of the base paper has a bulk density of below 0.85 g/cu. cm and a printing smoothness of above 15% (pressure: 20 kg/sq. cm) as measured by means of a printing smoothness tester.</p>
