Recent first-principles studies on antiferromagnetic oxide surfaces of MnO(001) and NiO(001) are reviewed. By structural optimization for the surface relaxation, small surface contraction and rampling relaxation where the surface transition-metal ions are displaced outwards are obtained. Surface electronic structures of the both oxides are still insulating and the spin magnetic moment at the transition-metal site is almost unchanged from its bulk value. The most interesting feature is the existence of finite spin magnetic moment at the surface oxygen site despite of no moment at oxygen in bulk by symmetry. The surface spin density distribution may be possibly observed by using exchange force microscopy technique recently proposed.