The endodermis plays a pivotal role as a selective barrier in the root, regulating of water and nutrient transport from the epidermis to the vasculature. Despite its important role, the mechanisms controlling root endodermis development remain largely unknown. In this study, we investigated endodermis development in the root apical meristem (RAM) by transverse section, and we found that the endodermal cells did not divide alongside RAM, unlike other types of root cells such as vascular cells. However, intriguingly, our findings revealed an increase in endodermal cell numbers in EN7::ΔARF5 and SCR::ΔARF5 transgenic plants which activate endodermis-specific auxin responses by expressing truncated ARF5 (ΔARF5) under the control of EN7 and SCR promoters. This suggests that endodermis division is regulated by auxin response. Further support for this idea came from the examination of DR5::VENUS/EN7::ΔARF5 and SCR::ΔARF5-GFP transgenic plants. Unlike wild-type plants transformed with DR5::VENUS, EN7::ΔARF5 plants transformed with DR5::VENUS (DR5::VENUS/EN7::ΔARF5) displayed an auxin response in endodermal cells, and the GFP fluorescent signals in SCR::ΔARF5-GFP transgenic plants clearly showed the periclinal division of endodermis in the SCR::ΔARF5-GFP. Additionally, our study showed that EN7::ΔARF5 and SCR::ΔARF5 transgenic plants promoted lateral root formation compared to wild-type plants. Taken together, these results suggest that endodermal cell division, which is regulated by auxin, is deeply involved in the development of lateral roots.