A pyridazine compound represented by formula (1):wherein A represents a nitrogen atom or a CR6, R1 represents a C2-C10 alkyl group having one or more halogen atoms, etc., R2 and R3 represent independently of each other a hydrogen atom, etc., R4 represents a C1-C6 chain hydrocarbon group optionally having one or more halogen atoms, R5 represents a C1-C6 chain hydrocarbon group optionally having one or more halogen atoms, etc., R6 represents a hydrogen atom, etc., n represents 0, 1, or 2, and p represents 0, 1, or 2, has an excellent efficacy for controlling harmful arthropods.
