Grinding machines are a main force in grinding work and various types of grinding machines have been developed and used. In today's industry, where particles need to be ground down to smaller size than ever before, utilization of bead mills, a type of agitated media mill, can be an effective grinding method. On the other hand, not enough study has been made on the bead mill because it is still new in the history of the grinding machine. In this study, grinding tests were thus conducted with a dry-type bead mill, using different sizes of beads. As a result, the distribution of particle diameters changed in a similar way, regardless of the bead size, as the grinding proceeded. Further, for all bead diameters, the relationship between specific energy and median diameter followed the same rule, which demonstrated that use of smaller beads increases energy efficiency in relative terms.