Homogenization of plant tissue is an important process for various experiments with plants. Because the commonly used mortar and pestle is laborious and time-consuming, the Finger Masher, a new type of vessel made of flexible plastic with a rough interior surface, was developed by Mizuho-Medy Co. Ltd. for rapid, easy homogenizations. Hands become too fatigued, however, when many samples must be processed. Therefore, we developed an automatic macerating machine for the Finger Masher to handle many samples in a short time. ELISA values obtained for Apple stem grooving virus or Cucumber mosaic virus in plant samples extracted with the automatic macerating machine were similar to those obtained by conventional homogenization with a mortar and pestle. The time for sample preparation was also much shorter than for other methods.