The invention of the present application provides a compound represented by formula (I) or a salt thereof, which exhibits an inhibitory activity against at least one kinase selected from the group consisting of Akt kinase, Rsk kinase and S6K kinase and/or a cell proliferation inhibiting effect and is useful as a prophylactic and/or therapeutic agent for diseases associated with the above-mentioned kinases, particularly cancer. [In the formula, R1 represents a 4- to 6-membered monocyclic unsaturated heterocyclic group which has 1 to 3 hetero atoms independently selected from N, S and O and may have a substituent； R2 represents a hydrogen atom or the like； R3, R4 and R5 may be the same as or different from one another and independently represent a hydrogen atom or the like； R6 represents a hydrogen atom or the like； R7 and R8 may be the same as or different from each other and independently represent a hydrogen atom or the like； X1 and X2 may be the same as or different from each other and independently represent N or CR9； R9 represents a hydrogen atom or the like； and X3 represents N or CH when the broken line (---) represents a single bond, and represents C when the broken line represents a double bond； wherein at least one of X1 and X2 represents N.]
