To provide a polymerizable monomer useful for a dental composite resin which has small polymerization shrinkage in curing, excellent operability, excellent mechanical strength of cured products, and a thermal expansion coefficient comparable to that of natural teeth.SOLUTION: The polymerizable monomer is represented by the general formula (1) in the figure. {In the formula, Rto Rare each independently a C1-20 hydrocarbon group (free of silicon atoms)； and Xand Xare each independently a (meth)acryloxy group or a (meth)acrylamide group.}SELECTED DRAWING: None【課題】硬化時の重合収縮が小さく、操作性に優れ、硬化物の機械的強度に優れ、かつ天然歯に近い熱膨張係数を有する、歯科用コンポジットレジンに有用な重合性単量体を提供する。【解決手段】下記一般式（１）｛式中、Ｒ1～Ｒ4はそれぞれ独立に炭素数１～２０の炭化水素基（但しケイ素原子を含まない）であり、Ｘ1、Ｘ2はそれぞれ独立に（メタ）アクリロキシ基、又は（メタ）アクリルアミド基である｝で表される重合性単量体。【選択図】なし
