The 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 Y 1 , Y 2 , Y 3 , and Y 4 represent C-R 3 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 R 1 represents a hydrogen atom, an optionally substituted alkyl group having 1 to 6 carbon atoms etc. R 2 represents a hydrogen atom, a halogen atom etc. R 3 represents a hydrogen atom, a halogen atom etc. R 4 and R 5 are the same or different and represent a hydroxyl group etc. R 6 and R 7 are the same or different and represent a hydrogen atom, an alkyl group having 1 to 6 carbon atoms etc. and R 8 represents an optionally substituted cycloalkyl group having 3 to 7 carbon atoms etc.HSP90 저해 작용을 갖고, 또한 세포 증식 억제 효과를 갖는 신규 인다졸 화합물을 제공하는 것에 있다. 또한 본 발명의 다른 과제는 HSP90 저해 작용에 기초하여, 그 HSP90 이 관여하는 질환, 특히 암의 예방 및/또는 치료에 유용한 의약을 제공한다.하기 일반식 (I)(식 중, X, Y1 ∼ Y4, A, B, R1 ∼ R8 은 본원 청구항에 기재된 바와 같다) 로 나타내는 화합물 또는 그 염.
