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Headstream areas, which are located in the uppermost reaches of mountain streams, are important sections for investigating the geomorphology of stream channels and their generative mechanisms, because they are close to sediment supply sources and generally suffer little anthropogenic impacts. In this study, the occurrences and characteristics of bed morphologies in a sandstone-dominated headstream area are explored at two scales—reach and unit—which are often overlooked. As a result of field investigations, cascades and step–pools were found to occupy the majority of the stream channel laterally at the reach scale. However, most of the elevation differences were accounted for by fall–pools, cascades, and step–pools, suggesting the importance of bed morphologies with large elevation losses in the headstream area. In addition, the characteristics of the bed morphologies at the reach scale were closely related to the longitudinal profiles of each stream. The mean gradients of the reach-scale bed morphologies were 46.9% for fall–pools, 23.9% for cascades, 16.8% for step–pools, and 5.9% for pool–riffles. At the unit scale, pools occupied the majority of the stream laterally, and > 80% of the elevation differences in all the studied rivers were occupied by falls, bedrock cascades, cascades, and steps. Although there have been no studies on the elevation loss functions and characteristics of falls, this study revealed the importance of fall–pool reaches and fall units in a sandstone-dominated headwater area in the Kantō Range of Japan. [ABSTRACT FROM AUTHOR]