This invention relates to a transparent composite material having a low coefficient of liner thermal expansion and excellent transparency and flexibility, which is formed by curing a resin composition containing urethane (meth)acrylate, in which 10 to 40% by mass of synthetic smectite that is organized with a quaternary ammonium salt and/or a quaternary phosphonium salt and has a number average particle diameter of from 10 to 300 nm and an aspect ratio of from 10 to 300 is dispersed; and a transparent composite sheet using the material.