Touch interfaces utilize mechanical vibration to give haptic feedback during operation. Lateral motion, that is, a vibration of the touch surface in the in-plane direction, is one of the methods used in haptic displays. Regarding lateral motion, we investigated the relationships between the displacement direction of the touch surface and the strength of the perceived stimulus. The targets for evaluation were perceived strength of stimuli in which the first-displacement directions of vibration were 0°, 90°, 180° and 270° against the proximal direction of the right index finger. A subjective evaluation was conducted and analyzed by using Scheffe's paired comparison method. It was shown that there was a statistically significant difference between the vibration group displaced in the long axis direction of the finger (0°, 180°) and that displaced in the short axis direction (90°, 270°). The result showed that the former was perceived to be stronger than the latter.