To provide a compound which exhibits excellent anti-tumor activity and excellent oral absorption and which is a useful anti-tumor drug.The invention provides a 3-ethynylcytidine derivative represented by formula (1):(wherein X represents a (substituted) alkylcarbonyl group, a (substituted) alkoxycarbonyl group, or a hydrogen atom one of Y and Z represents a hydrogen atom or a group represented by (R1) (R2) (R3) Si- and the other represents a group represented by (R4) (R5) (R6) Si- and R1, R2, R3, R4, R5, and R6each represent a (substituted) alkyl group, a (substituted) cyclic alkyl group, or a (substituted) aryl group) or a salt thereof.本發明係提供一種顯示優良抗腫瘤活性、並且具有優良經口吸收性、可用作抗腫瘤劑之化合物。本發明係一種3-乙炔基胞嘧啶核苷衍生物或其鹽,其係以下述通式(1)所表示者;[式中,X表示(經取代)烷基羰基、(經取代)烷氧基羰基或氫原子,Y及Z中之一者表示氫原子或以(R1)(R2)(R3)Si-表示之基,另一者表示以(R4)(R5)(R6)Si-表示之基,R1、R2、R3、R4、R5及R6表示(經取代)烷基、(經取代)環狀烷基、或(經取代)芳基]。
