A compound represented by the general formula (M): (wherein R 1 represents a substituted or unsubstituted aromatic heterocyclic group, R 2 represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, OR 3 , N(R 3 ) 2 , C(=O)OR 3 or C(=O)N(R 3 ) 2 , R 3 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, or an acyl group having 1 to 4 carbon atoms, R 4 represents a hydrogen atom, an oxygen atom or OR 5 , and R 5 represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or an acyl group having 1 to 3 carbon atoms); or a pharmaceutically acceptable salt thereof is a cortistatin A analog which is useful as an active ingredient of medicaments for cancer prevention or treatment in that the analog can be mass-produced by chemical synthesis due to its simple chemical structure and retains the same biological activities as those of cortistatin A.