The present invention is to provide an oxopyrazine derivative having an excellent herbicidal activity and besides exhibiting high safety for useful crops and the like, or a salt thereof, and a herbicide containing the same.The present invention relates to an oxopyrazine derivative represented by formula [I]:wherein X1 represents an oxygen atom or a sulfur atom； X2 represents CH or N(O)m； m represents an integer of 0 or 1； R1 represents a hydrogen atom, a C1-C12 alkyl group and the like； R2 represents a halogen atom, a cyano group and the like； R3 is a hydroxyl group, a halogen atom and the like； A1 represents C(R4R5)； A2 represents C(R6R7) or C═O； A3 represents C(R8R9)； R4 to R9 represent a hydrogen atom or an alkyl group,or a salt thereof, and a herbicide containing these compounds.
