A process for producing an imidazo[1,2-b]pyridazine compound represented by the formula (2): wherein R1, R2 and R3 are the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group which may be substituted with a halogen atom or atoms, an alkenyl group which may be substituted with a halogen atom or atoms, or an alkoxy group which may be substituted with a halogen atom or atoms, which comprises reacting a 2,3-dihydropyridazine compound represented by the formula (1): wherein R1, R2 and R3 are the same meanings as defined above, with a phosphorus oxyhalide in the presence of an organic base which is in an amount of 0.5 mole or more relative to 1 mole of the 2,3-dihydropyridazine compound and 1 mole or less relative to 1 mole of the phosphorus oxyhalide.