The pressure of expansive concrete under confinement was investigated by the finite element method (FEM). It was found that it was possible to estimate the pressure of expansive concrete by simple elastic calculation using FEM where the elastic modulus was assumed to be 1-3 GPa, which was an order of magnitude lower than that of normal concrete. Experimental data giving the pressure of expansive concrete under confinement was successfully explained by the FEM calculation. It is demonstrated that FEM analysis is a useful tool to estimate the pressure of expansive concrete under various confinement conditions.