<p>[PROBLEMS] To provide a novel compound capable of inhibiting the activity of HSP90, particularly a novel compound capable of inhibiting the chaperon protein function of HSP90 and having an anti-tumor activity. [MEANS FOR SOLVING PROBLEMS] A pyrazolopyrimidine compound represented by the formula (1) having various substituents, which is capable of inhibiting the ATPase activity of HSP90 and has an anti-tumor activity; an HSP90 inhibitor comprising the compound represented by the formula (1); a pharmaceutical agent comprising the compound represented by the formula (1); an anti-cancer agent comprising the compound represented by the formula (1); a pharmaceutical composition comprising the compound represented by the formula (1); a method for the treatment of cancer by using the compound represented by the formula (1); and others. (1)</p>
