The present invention provides crystals of (1R,3R,15E,28R,29R,30R,31R,34R,36R,39S,41R)-29,41-Difluoro-34,39-bis(sulfanyl)-2,33,35,38,40,42-hexaoxa-4,6,9,11,13,18,20,22,25,27-decaaza-34λ5,39λ5-diphosphaoctacyclo[28.6.4.13,36.128,31.04,8.07,12.019,24.023,27]dotetraconta-5,7,9,11,15,19,21,23,25-nonaene-34,39-dione (Compound (I)) ammonium salts, Compound (I) sodium salts, or Compound (I), possessing a potential to be used as drug substance in pharmaceuticals.