A bisguanidine salt selected from the group consisting of a 4-(phenylsulfonyl)phenylsulfonylacetic acid salt of N,N'-bis(1,3-diethylguanyl)ethylenediamine, a 4-(phenylsulfonyl)phenylsulfonylacetic acid salt of N,N'-bis(1,3-diisopropylguanyl)ethylenediamine, a 4-(phenylsulfonyl)phenylsulfonylacetic acid salt of N,N'-bis-(imidazoline-2-yl)ethylenediamine, a 4-(phenylsulfonyl)-phenylsulfonylacetic acid salt of 1,4-bis(1,3-diisopropylguanyl)piperazine, a 4-(phenylsulfonyl)phenylsulfonylacetic acid salt of 1,4-bis(1,3-diethylguanyl)piperazine, a 4-(4-methylphenylsulfonyl)phenylsulfonylacetic acid salt of N,N'-bis(1,3-diethylguanyl)ethylenediamine and a 4-(4-ethylphenylsulfonyl)phenylsulfonylacetic acid salt of 1,4-bis(1,3-diethylguanyl)piperazine, for a heat-developable photographic material and a heat-sensitive recording material.