Scratch behavior in glass is very important to understand the interaction between the abrasive particles and the glass product during grinding. In addition, the chipping problem in glass often appears during the glass manufacturing process. A thin sheet glass, such as an LCD (Liquid Crystal Display) or PDP (Plasma Display Panel) glass, is susceptible to scratches, a brasions, rubbing and chipping, which are mechanical failures caused by a dynamical contact between the glass and a foreign body. In order to suppress these contact problems and to develop a glass with high wearability, it is essential to understand the mechanical response to a scratch as the cumulative actions of a hard material. It is considered that a scratch test is one of the fundamental testing methods to evaluate these mechanical properties. However, only a few papers have been published on scratch behaviors in glass.1–3 Especially, the origin of scratch groove formation has little been understood. The formation of scratch groove is probably related to microscopic fracture, plastic deformation, and material removal. The scratch test surely gives us some important information on the damageability of glasses with various compositions under various conditions.