This invention provides a silicone monomer which has a high silicone content, has the high transparency and oxygen transmission rate when being copolymerized with polymerizable monomers such as a (meth)acrylic monomer, and is suitable for application to the eye a preparation method thereof and a monomer composition and a polymer using the monomer. This silicon monomer is represented by the formula (1) (R: H or CH3, X: a group selected from the formula (2a) - formula (2f), and n: 0 or 1.). The monomer is useful for producing eye devices such as contact lenses.本發明提供一種有機矽含量高,且與(甲基)丙烯酸系單體等聚合性單體共聚時,透明度及透氧率高的、適用於眼部的有機矽單體,其製備方法、使用該有機矽單體的單體組合物及聚合物。所述有機矽單體具有式(1)所示的結構,R:H或CH3;X:選自式(2a)~式(2f)所示的基團;n:0或1。該單體適用於製備角膜接觸鏡等眼部器具。
