The present invention is (1S) -1,5- anhydro-1- [3-1- (benzothiene-2-ylmethyl) -4-fluorophenyl] -D- gluconic when a ball of the toll and L- proline It relates to the decision. The crystal ball is excellent in storage stability at the same time having a constant quality, a suitable ball determined with a known compound A as crystals of wonyak providing a drug having no moisture absorption.(1S) -1,5- anhydro-1- [3-1- (benzothiene-2-ylmethyl) -4-fluorophenyl] -D- glucitol, L- proline, crystal balls, constant quality storage stability, hygroscopic본 발명은 (1S)-1,5-안하이드로-1-[3-1-(벤조티엔-2-일메틸)-4-플루오로페닐]-D-글루시톨과 L-프롤린과의 공결정에 관한 것이다. 상기 공결정은 일정한 품질을 갖는 동시에 보존 안정성이 우수하고, 흡습성을 갖지 않는 의약품에 제공하는 원약의 결정으로서 적합한, 공지 화합물 A와의 공결정이다.