Crystalline form of 3-((L-valyl) amino)-1-propanesulfonic acid

A crystalline form of 3-((L-valyl)amino)-1-propanesulfonic acid, characterized in that said crystalline form exhibits characteristic diffraction peaks at 2θ diffraction angles of 9.4°, 11.1°, 15.9°, 17.8°, 18.4°, 21.0°, and 22.5° in an X-ray powder diffraction pattern using Cu-Kα as a radiation source, wherein 2θ has an error range of ±0.2°, and a starting melt temperature of a differential scanning calorimetry curve of said crystalline form is about 301° C. or higher.