PROBLEM TO BE SOLVED: To provide a novel IL-17 expression inhibitor. SOLUTION: A carbon chain having isoprene as a constitutional unit and sometimes having a branched chain, in which a carbon-carbon single bond and a carbon-carbon double bond are alternately continuous in the carbon chain. An IL-17 expression inhibitor containing a terpene having a structure or a derivative thereof or a salt thereof. [Selection diagram] None【課題】新たなＩＬ－１７発現抑制剤の提供。【解決手段】イソプレンを構成単位とし分岐鎖を有することもある直鎖炭素鎖状で且つ当該炭素鎖中に炭素－炭素の単結合と炭素－炭素の二重結合とが交互に連続する炭素鎖構造を有するテルペンもしくはその誘導体またはそれらの塩を含有するＩＬ－１７発現抑制剤。【選択図】なし
