Insect herbivores give negative or positive plant-mediated effects on other herbivores as indirect effects due to their host plant. We investigated plant-mediated effects of the stem gall wasp, Dryocosmus kuriphilus, on other herbivores through regrowth response on chestnut trees, Castanea crenata. We randomly selected a pair of 1-year-old shoots with and without galls as a sample. The host plant properties in terms of leaf number, thickness, toughness, and its qualities were measured. Field study showed that gall initiation stimulated earlier expansion of new leaves with higher number on May. Leaves emerged from galled shoots were tougher and thicker, and also had higher nitrogen but low water content. In addition, the galled shoot tended to accelerate maturation of leaves than normal shoot. The abundance of aphid, Myzocalis kurichola, was significantly higher on new leaves with galls. These results suggested that gall makers gave an indirect positive effect on aphid abundance by altering new leaf formation time.