The present invention provides a pyarzoloquinolone derivative having kinase inhibitory activity. The derivative is represented by the formula: wherein R1 is an aryl group which may be substituted, or an aromatic heterocyclic group which may be substituted; R2 is a hydrogen atom, an amino group which may be substituted, a hydroxy group which may be substituted, or a thiol group which may be substituted; R3, R4, R5 and R6, which may be identical or different, are each (1) a hydrogen atom, (2) a nitro group, (3) a cyano group, (4) a halogen atom, (5) a hydrocarbon group which may be substituted, (6) an amino group which may be substituted, (7) a hydroxy group which may be substituted, or (8) a thiol group which may be substituted; and R3 and R4, R4 and R5, and R5 and R6 may respectively form a ring together with the adjacent carbon atom, or salt thereof.