And exhibits excellent antitumor activity, had oral absorption excellent, providing a compound useful as an antitumor agent. The following general formula (1) Wherein, (substituted) alkyl group, a hydrogen atom or a (substituted) alkoxycarbonyl group, one table (R 1) (R 2) a (R 3) Si- hydrogen atom or Z and Y and X and a group represented by (R 4) (R 5) with (R 6) Si- group that is, the other, R 6 and 4, R 5 R 1, R 2, R 3, R is (substituted) alkyl I show the (substituted) aryl group group, or (substituted) cyclic alkyl group,. Or a salt thereof 3ethynylcytidine derivative represented by].優れた抗腫瘍活性を示すとともに、優れた経口吸収性を有し、抗腫瘍剤として有用な化合物の提供。下記一般式(1)[式中、Xは(置換)アルキルカルボニル基、(置換)アルコキシカルボニル基又は水素原子を示し、Y及びZは一方が水素原子又は(R1)(R2)(R3)Si-で表される基、他方が(R4)(R5)(R6)Si-で表される基を示し、R1、R2、R3、R4、R5及びR6は(置換)アルキル基、(置換)環状アルキル基、又は(置換)アリール基を示す。]で表される3’-エチニルシチジン誘導体又はその塩。
