The tactile detectability of sinusoidal and squarewave virtual texture gratings were measured and analyzed. Using a three-interval one-up three-down adaptive tracking procedure, detection thresholds for virtual gratings were estimated using a customdesigned high position-resolution 3-degrees-offreedom force-feedback haptic device. Two types of gratings were used, defined by sinusoidal and square waveforms, with spatial wavelengths of 0.2 to 25.6 mm. The results indicated that the participants demonstrated a higher sensitivity (i.e., lower detection threshold) to square-wave gratings than to sinusoidal ones at all the wavelengths tested. When the squarewave gratings were represented by the explicative Fourier series, it became apparent that the detectability of the square-wave gratings could be determined by that of the sinusoidal gratings at the corresponding fundamental frequencies. This was true for any square-wave grating as long as the detection threshold for the fundamental component was below those of the harmonic components.