In a haptic shape task, the human ability to discriminate objects on basis of their shape, as defined by active exploratory movements of the hand, is dependent on receptors located in the skin and deep structures. The shape of a 2-d object is a function of its geometric properties, including the pattern of the surfaces that form the object, their density, their size, and their spatial features. It is now widely known that haptic shape task shares neural activity in visual cortical areas, but we have little information about the factors for haptic shape perception. We investigated to what factors of pattern play an important role in a haptic shape discrimination task. Haptic shape can be gained through a small braille device. There are 10 baselines in the experiment, and 6 kinds of other patterns based on each baseline were made. Healthy right-handed subjects performed a delayed-match-to sample task discriminating between pairs of two-dimensional patterns. From the different characteristics of difficulty in the pattern task, we concluded that different difficulty in discrimination task are underling haptic shape patterns with different densities and sizes.