Heat-sensitive recording material

A heat-sensitive recording material comprising in sequence a support, a heat-sensitive recording layer which is provided on the support and contains at least two types of compound which react with each other to develop color by heating imagewise, and a protective layer, wherein at least one of the layers contains the compound represented by the following formula (I):

• R—(S—P)n Formula (I)
• wherein R represents a hydrophobic group or a hydrophobic polymer, P represents a polymer including at least one of the below-described structural units A, B, and C, and having a polymerization degree which ranges from 10 to 3500, and n represents 1 or 2,
• wherein R1 represents —H or an alkyl group having 1 to 6 carbon atoms, R2represents —H or an alkyl group having 1 to 10 carbon atoms, R3 represents —H or —CH3, R4 represents H, —CH3, —CH2COOH or an ammonium salt thereof or a metallic salt thereof or —CN, X represents —H, —COOH or an ammonium salt thereof or a metallic salt thereof or —CONH2, and Y represents —COOH or an ammonium salt thereof or a metallic salt thereof, —SO3H or an ammonium salt thereof or a metallic salt thereof, —OSO3H or an ammonium salt thereof or a metallic salt thereof, —CH2SO3H or an ammonium salt thereof or a metallic salt thereof, —CONHC(CH3)2CH2SO3H or an ammonium salt thereof or a metallic salt thereof or —CONHCH2CH2CH2N+(CH3)3C−.