We investigated roughening of a single-crystal silicon surface during chemical anisotropic etching using KOH water solution. The change in roughness strongly depends on the crystallographic orientation of the silicon. We plotted a map showing roughness distribution as a function of orientation. A smooth surface appears in a region including the [100], [211], and [311] planes. A very rough surface appears in a region including the [320] and [210] planes. We further clarified that the roughened surface shows facet textures composed of certain crystallographic planes. This result suggests that the orientation-dependent etching rate and surface roughening are closely related.