Disclosed is a heat-sensitive recording material comprising a support and a heat-sensitive recording layer formed on the support, the heat-sensitive recording layer containing dye precursor-containing composite particles and a developer, the dye precursor-containing composite particles being obtained by dissolving a solute containing a dye precursor in a solvent containing a polyvalent isocyanate compound-containing polymerization component, emulsifying and dispersing the obtained solution in an aqueous medium, and then performing a polymerization reaction of the polyvalent isocyanate compound-containing polymerization component in the presence of polyethyleneimine having a molecular weight of 200 to 1,500. Also disclosed is a method of producing such a heat-sensitive recording material.