The present invention provides an excellent ant controller for protecting wooden materials such as trees, board fences, sleepers, etc. and structures such as shrines, temples, houses, outhouses, factories, etc. from termites, and for controlling ants doing harm to crops or humans, which contains as active ingredient thereof a hydrazine derivative represented by general formula (I) [wherein A represents one of formulas (II), (III), (IV), and (V), (wherein R4 and R5 are H, C1-C6 alkyl, etc.； X is 1 to 5 substituents selected from H, halogen and (halo) C1-C6 alkyl)； R1 is H or C1-C6 alkyl； R2 and R3 are H, OH, C1-C6 alkyl, phenylcarbonyl, etc.； Y is 1 to 5 substituents selected from H, halogen, nitro and cyano； Z is halogen, cyano, C1-C6 alkyl, etc.； and W is O or S]； and a method for application of the ant controller.
