The polymerization of styrene mechanochemically initiated by the wet grinding of quartz was attempted by using a vibrating ball mill with a laboratory scale. The effect of the grinding of quartz on the polymerization of the styrene was investigated by characterizing the polymer formed and the quartz ground. The results showed that styrene could also mechanochemically polymerize by the resulting active species of the grinding of quartz as well as methyl metbacrylate. The polymerization was found closely related to the total surface area of the ground quartz. The molecular weight distributions of the polymer formed were not simply unimodal and remarkably broader than those of the methyl methacrylate. It was suggested that the polymerization of the styrene proceeded with a cationic active species from the experimental results and discussions.