In this study, we developed a testing method using photogrammetry (SfM) to determine the erosion control effect of vegetation works against surface water along a slope. The test was conducted by two types of specimens: one with compacting cohesive soil and the other with growth of herbaceous plants. Test equipment comprises a slope stage and a water path with a tank. Water which overflows the tank flows downwards along the specimen surface. Photos were taken after the tests to create three-dimensional models using Metashape from Agisoft, and we measured the erosion volume therewith. These experiment results show that the stem and leaves, and root systems of herbaceous plants significantly delay the erosion start time. However, it was also found that once erosion began and vegetation was swept away, the erosion control effect was lost.