The present invention provides a novel compound that inhibits the action of HSP90, especially provides the novel compound that inhibits the function as the chaperon protein of HSP90, and has the antitumor activity. This invention provides the pyrazolopyrimidine compound of the following general formula (1) that can inhibit the ATPase activity of HSP90 and have the antitumor activity. The HSP90 inhibitor including the compound shown by the formula (1), the medicine including the compound shown by the formula (1), the anti-cancer drug including the compound shown by the formula (1), the pharmaceutical composition including the compound shown by the formula (1) and the method of treatment of cancer. by using the pyrazolopyrimidine compound of the following general formula (1) with various substituents etc are also provided.
