Abstract: (Wherein n is an integer of from 0 to 3; R1 is substituted or unsubstituted cycloalkyl, substituted or unsubstituted aryl, a substituted or unsubstituted alicyclic heterocyclic group, or a substituted or unsubstituted aromatic heterocyclic group; R2 is halogen, substituted or unsubstituted lower alkyl, substituted or unsubstituted aryl, a substituted or unsubstituted alicyclic heterocyclic group, a substituted or unsubstituted aromatic heterocyclic group, —COR8, or the like; R3 and R4 may be the same or different, and each represents a hydrogen atom, substituted or unsubstituted lower alkyl, substituted or unsubstituted aralkyl, —COR12, or the like) For example, provided are adenosine A2A receptor antagonists comprising, as the active ingredient, a thiazole derivative represented by a general formula (I), or a pharmaceutically acceptable salt thereof, and the like.