Volcanic eruptions can lead to the deposition of pyroclastic debris in mountainous regions, potentially triggering debris flows. According to Japanese law, the government must promptly conduct surveys when pyroclastic debris accumulates under specific conditions, one of which is the thickness of the pyroclastic deposits. Traditionally, this thickness is assessed visually from helicopters or through photo analysis instead of physical measurements. However, these methods are hindered by factors such as bad weather or nighttime conditions. Thus, using diverse survey methods is crucial for rapid evaluation. This study explores the feasibility of LiDAR (Light Detection and Ranging), increasingly popular in recent years, to measure the thickness of pyroclastic deposits. LiDAR is also capable of non‐contact, automatic measurement day and night. Results confirm that LiDAR is capable of accurate measurements and is a promising alternative for measuring pyroclastic deposits.