The present invention relates to an aminopyridine compound represented by the following general formula (I) or a salt thereof and an Syk inhibitor containing the compound or a salt thereof as an active ingredient. Here, X1, X2, X3, Z, Y1, Y2 represent a carbon atom or a nitrogen atom, R, R1, R5, R6 represent a hydrogen atom, an alkyl group, etc., and R7 represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, —CpH2(p-1)(Ra1)(Ra2)—O—Ra3, —C(═O)—Rd1, a 5- or 6-membered saturated heterocyclic group, an aromatic heterocyclic group, —N(Rh1)(Rh2), etc. The aminopyridine compound of the present invention has not only high Syk inhibitory activity but also properties to selectively inhibit Syk.