Monitoring of leaf phenology by using ground observation method has been considered as a time consuming and labor-intensive technique. Departing from this problem, the satellite-based remote sensing technique has been developed to monitor leaf phenology with a promising efficiency. However, this technique cannot be applied smoothly in the humid area, such as tropical zones and Japan, where cloud covers are frequently found over the target area and disrupting the observation. In addition, the coarse-resolution of the satellite image leads to the difficulties of obtaining detail information of leaf phenology at the individual-level. For this reason, remote sensing by using drones might be a convenient choice to overcome these issues since fine-resolution images covering large areas can be produced by this technique without spending too much time. This study was aimed to evaluate the ability of drone-based observation in capturing tree-level variation of leaf phenology by comparing the result with ground monitoring data. The observation was conducted in a cool-temperate deciduous forest of Japan’s South Alps in Shizuoka Prefecture at the elevation of 1,400 m above sea level. Aerial photographs were taken periodically by a commercial drone during the 2019 growing period along with ground monitoring. The results comparison between these two methods will be discussed.