The present invention provides a compound represented by the following general formula (I) or a salt thereof which has a Syk inhibitory effect (in the formula R1 represents a hydrogen atom or an optionally Ra-substituted C1-C6 alkyl group A represents a hydrogen atom, an optionally Ra-substituted C1-C8 alkyl group, an optionally Ra-substituted C2-C6 alkenyl group, an optionally Ra-substituted C2-C6 alkynyl group, an optionally Rb-substituted C3-C10 cycloalkyl group, an optionally Rb-substituted C6-C14 aromatic hydrocarbon group, an optionally Rb-substituted 4- to 10-membered unsaturated heterocyclic group, or an optionally Rb-substituted 4-to 10-membered saturated heterocyclic group, or optionally forms a 4- to 10-membered unsaturated heterocyclic ring or a 4- to 10-membered saturated heterocyclic ring together with R1 and the nitrogen atom bonded thereto R2 represents a hydrogen atom or an optionally Ra-substituted C1-C6 alkyl group and B represents an optionally Rc-substituted unsaturated heterocyclic group).
