To provide a novel compound inhibiting the effect of HSP90, in particular a novel compound inhibiting the function of HSP90 as a chaperone protein and having antitumor activity.The present invention provides a pyrazolopyrimidine compound represented by formula (1) having various substituents which inhibits the ATPase activity of HSP90 and which has antitumor activity, an HSP90 inhibitor comprising a compound represented by formula (1), a medicament comprising a compound represented by formula (1), an anticancer agent comprising a compound represented by formula (1), a pharmaceutical composition comprising a compound represented by formula (1), and a method for treating cancer using a compound represented by formula (1).
