Recently, poleward range expansions in association with recent climate warming have been reported in several species around the world. In Japan, Nezara viridula, a serious pest of various crops, has been expanding its range northward, possibly due to climate warming. Data on the current distribution and accurate prediction of range expansion are important for pest management. Here, we show that the current distribution of N. viridula in the Kinki district has been expanded northward. Moreover, comparison of the current distribution with the data from five and fifty years ago reveals that the speed of range expansion has accelerated. In addition, the current distribution cannot be simply explained by temperature, which was previously believed to determine the northern limit of N. viridula, because the temperature in the current northern limit area does not meet the conditions. This suggests that factors other than temperature are also involved in the northward range expansion of N. viridula. To understand the impact of climate warming on the northward range expansion, it is important to consider not only temperature but also other factors, including physiological and/or behavioral adaptations.