To provide a crystal of a tricyclic pyrazolopyrimidine compound inhibiting the effect of HSP90. The present invention provides a crystal of 2-{4-amino-2-[(3-chloro-4-methoxy-5-methylpyridin-2-yl)methyl]-2,7-dihydro-6-thia-1,2,3,5-tetraazabenzo[cd]azulen-8-yl}-N-methylacetamide which inhibits the ATPase activity of HSP90 and which has antitumor activity, a medicament comprising the same, an anticancer agent comprising the same, and the like.HSP90 의 작용을 저해하는 3 고리성 피라졸로피리미딘 화합물의 결정을 제공하는 것.본 발명은 HSP90 의 ATPase 활성을 저해하고, 항종양 활성을 갖는 2-{4-아미노-2-[(3-클로로-4-메톡시-5-메틸피리딘-2-일)메틸]-2,7-디하이드로-6-티아-1,2,3,5-테트라아자벤조[cd]아줄렌-8-일}-N-메틸아세트아미드의 결정 및 그들을 함유하는 의약, 항암제 등을 제공한다.
