There is provided a lipid peptide that is capable of forming a hydrogel with an extremely small amount thereof over a liquid property range from acidic to alkaline, and a hydrogel having high environmental suitability, biocompatibility and biodegradability. A lipid peptide represented by Formula (1): (where R 1 represents an aliphatic group having 9 to 23 carbon atoms R 2 , R 3 , R 4 and R 5 independently represent a hydrogen atom, an alkyl group having 1 to 7 carbon atom(s) which optionally has a branched chain having 1 to 3 carbon atom(s), a phenylmethyl group, a phenylethyl group or a -(CH 2 ) n -X group, and at least one of R 2 , R 3 , R 4 and R 5 represents a -(CH 2 ) n -X group n represents the number of 1 to 4 X represents an amino group, a guanidino group, a -CONH 2 group or a 5-membered ring, a 6-membered ring or a fused heterocyclic ring composed of a 5-membered ring and a 6-membered ring which optionally have 1 to 3 nitrogen atom(s) and m represents 1 or 2), and a hydrogel comprising the lipid peptide.本發明之課題在於提供於酸性至鹼性的液性範圍中以極少量可形成水凝膠之脂質肽以及具有高的環境.生物體適合性及生物分解性之水凝膠。解決上述課題之方法為式(1):(式中,R1表示碳原子數9至23的脂肪族基,R2、R3、R4及R5各自獨立地表示氫原子、可有碳原子數1至3的支鏈之碳原子數1至7的烷基、苯基甲基、苯基乙基或-(CH2)n-X基,且R2、R3、R4或R5中的至少一個表示-(CH2)n-X基,n表示1至4之數,X表示胺基、胍基、-CONH2基、或可有1至3個氮原子的5員環或6員環或由5員環與6員環所構成的縮合雜環,m表示1或2)所示的脂質肽及由其所成的水凝膠。
