Disclosed is a crystal of (R)-2-[[[3-methyl-4-(2,2,2-trifluoroethoxy)-2-pyridinyl]methyl]sulfinyl]-1H-benzimidazole wherein the powder X-ray diffraction analysis pattern has characteristic peaks at interplanar spacings (d) of 10.06 plus/minus 0.2, 8.70 plus/minus 0.2, 6.57 plus/minus 0.2, 5.59 plus/minus 0.2 and 4.00 plus/minus 0.2 Angstrom. Also disclosed is a pharmaceutical agent comprising the crystal and the use of the crystal for the production of an agent for the prophylaxis or treatment of peptic ulcer, Zollinger-Ellison syndrome, gastritis, reflux esophagitis, symptomatic gastroesophageal reflux disease (Symptomatic GERD), Barretts oesophagus, functional dyspepsia, gastric cancer, stomach MALT lymphoma, ulcer caused by a non-steroidal anti-inflammatory agent, or hyperacidity or ulcer due to postoperative stress or an inhibitor of upper gastrointestinal haemorrhage due to peptic ulcer, acute stress ulcer, haemorrhagic gastritis or invasive stress.
