A gelling agent was dissolved and dispersed by heating and stirring the medium, stirring was allowed to cool while, at room temperature even hydrogel formed when through the steps to stand in the hydrogel-forming material, as well as, hydrogels the even after sol by shaking, to then provide a room temperature re-formation of a gel by standing at the hydrogel material. A lipid peptide-type gelling agent comprising a compound represented by the following formula (1), and water, containing a fatty acid salt as an additive, hydrogel-forming material. (In the formula, R 1 represents an aliphatic group having a carbon number of 9 to 23, R 2 is a hydrogen atom, or an alkyl group having 1 to 4 carbon atoms which may have a branched chain carbon atoms 1 or 2 the stands, R 3 is - (CH2) represents an n -X group, n represents a number from 1 to 4, X is an amino group, a guanidino group, -CONH 2 group, or a nitrogen atom and 1 to 3 Yes from then it may 5- or 6-membered ring or 5-membered ring and 6-membered ring represents a fused heterocyclic ring composed.)【課題】ゲル化剤を媒体に加熱撹拌して溶解・分散させた後に、撹拌しながら放冷後、室温で静置する工程を経た場合においてもヒドロゲル形成が可能なヒドロゲル形成材料、並びに、ヒドロゲルを振とうによりゾル化した後においても、その後室温で静置することでゲルの再形成が可能なヒドロゲル材料を提供すること。【解決手段】下記式(1)で表される化合物又はその塩からなる脂質ペプチド型ゲル化剤と、水と、添加剤として脂肪酸塩とを含有する、ヒドロゲル形成材料。(式中、R1は炭素原子数9乃至23の脂肪族基を表し、R2は水素原子、又は炭素原子数1若しくは2の分枝鎖を有し得る炭素原子数1乃至4のアルキル基を表し、R3は-(CH2)n-X基を表し、nは1乃至4の数を表し、Xはアミノ基、グアニジノ基、-CONH2基、又は窒素原子を1乃至3個有し得る5員環若しくは6員環又は5員環と6員環から構成される縮合複素環を表す。)
