Two-dimensionally ion-conductive liquid crystals have been simply obtained by self-assembly of a cholesterol/tetra(ethylene oxide) block molecule and lithium triflate. Nanophase-segregation between cholesterol and tetra(ethylene oxide) blocks leads to the formation of a smectic A liquid crystalline phase in a wide range of temperature. A homeotropically aligned lithium salt complex in the smectic A phase shows two-dimensional ionic conductivity. The ionic conductivities parallel to the smectic layers are higher than those perpendicular to the layers. The maximum value of the anisotropy in the ionic conductivity is about 2.4 x 10(3) at 30 degrees C.