A new method for phase-shifting moiré interferometry is proposed and studied experimentally. A nematic liquid crystal cell is employed as a phase modulator to realize the phase-shifting technique for the conventional moiré interferometry. The phase retardation of the liquid crystal cell is calibrated by measuring transmitted light intensities. By letting one of coherent beams pass through a liquid crystal cell and controlling the phase retardation via suitable voltages across the cell, the phase map that provides quantitative data regarding the in-plane surface displacement can be created. The use of the liquid crystal phase modulator in the moiré optical arrangement has several advantages over alternative methods.