Provided is a transparent composite material having a low linear expansion coefficient and excellent transparency and flexibility. Also provided is a transparent composite sheet using said material. The transparent composite material is formed by curing a resin composite created by dispersing, into a resin component containing urethane (meth)acrylate, 10-40% by mass of a synthetic smectite having a numerical average particle diameter between 10 and 300 nm and an aspect ratio between 10 and 300, that has been organically modified by quaternary ammonium salt and/or quaternary phosphonium salt.