Outdoor brands often use streamlined cutting lines to design high-performance outdoor pants. Inappropriate design lines combined with the accompanying sewing lines can cause discomfort or even restrict body movement. To reduce such discomfort, we need to find the appropriate location for cutting lines that do not interfere with body movement. In this research, we conducted ergonomic mapping of skin deformation in dynamic postures to provide fundamental data for selecting functional design lines of pants that will not hinder various movements. To analyze the lower body skin deformation depending on the posture, we marked dots at 3 cm intervals on the leg. We then measured the change in length between the points for three different postures using a three-dimensional scanner and the Rapidform program. The results were shown as a skin deformation map; this is expected to be used as reference data for the functional design lines of streamlined outdoor pants.