There is provided a hydrogel-forming material from which a hydrogel can be formed with a simpler method and under milder conditions. A hydrogel-forming material comprising a lipid peptide-type gelator that is formed of at least one selected from compound of the following formula (1): where R1 is a C9-23 aliphatic group; R2 is a hydrogen atom or a C1-4 alkyl group which optionally has a C1-2 branched chain; R3 is a —(CH2)n—X group; n is a number from 1 to 4; and X is an amino group, a guanidino group, a —CONH2 group, or a 5-membered ring group or a 6-membered ring group, or a condensed ring group that contains a 5-membered ring and a 6-membered ring, optionally containing 1 to 3 nitrogen atoms, and the similar compounds or pharmaceutically usable salts thereof; water; and an additive including either an organic acid or an organic acid salt.