The present invention relates to provision of a novel indazole compound which is capable of inhibiting HSP90 and shows a cytostatic effect on cancer cells. The present invention also relates to provision of a drug useful for preventing and/or treating, on the basis of an HSP90 inhibitory effect, a disease in which HSP90 participates, in particular, cancer. A compound represented by the general formula (I) or a salt thereof: wherein X represents CH or N; any one or two of Y1, Y2, Y3, and Y4 represent C—R3 or N, and the others represent CH; A and B are the same or different and represent an optionally substituted monocyclic unsaturated heterocyclic group having 1 to 4 heteroatoms selected from N, S, and O; R1 represents a hydrogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms etc.; R2 represents a hydrogen atom, a halogen atom etc.; R3 represents a hydrogen atom, a halogen atom etc.; R4 and R5 are the same or different and represent a hydroxyl group etc.; R6 and R7 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms etc.; and R8 represents an optionally substituted cycloalkyl group having 3 to 7 carbon atoms etc.