The present invention provides a gelling agent and a gel-like composition which can solve an oil-based agent such as a silicone oil at low temperature and show excellent gelling property.It is a gelling agent comprising an amino acid oligomer derivative. The amino acid oligomer derivative is formed by acylating at least one selected from the end and the side chain of an amino acid oligomer. The amino acid oligomer derivative is a polycondensate of a monomer comprising an amino monomer.本發明提供一種能在低溫下溶解如矽油之油性基劑、並顯示優良的凝膠化能力的膠凝劑及凝膠狀組成物。其係一種包含胺基酸低聚物衍生物之膠凝劑。該胺基酸低聚物衍生物係將胺基酸低聚物之末端或側鏈的至少一者醯化而成。該胺基酸低聚物係包含胺基酸單體之單聚物的聚縮合物。
