It is intended to provide a novel azabicyclo compound whichexhibits both HSP90 inhibitory activity and cell proliferationinhibitory effect. Specifically disclosed is a compoundrepresented by the following general formula (I) or a saltthereof: wherein X1 represents CH or N； any one of X2, X3 and X4represents N, and the others represent CH； any one or two of Y1,Y2, Y3 and Y4 represent C-R4, and the others are the same ordifferent and represent CH or N； R1 represents an optionallysubstituted monocyclic or bicyclic unsaturated heterocyclic grouphaving 1 to 4 heteroatoms selected from N, S and O； R2 representsan alkyl group having 1 to 6 carbon atoms, or the like； and R3 andR4 represent -CO-R5 or the like.
