An object of the present invention is to provide a method for industrially manufacturing a nitrogen-containing heterocyclic compound which shows excellent FLT3 inhibitory activity and is useful as a pharmaceutical active ingredient of pharmaceutical products. The present invention provides a manufacturing method of a compound represented by General Formula [14] or a salt thereof (in the formula, R 1 represents a C 1-6 alkyl group which may be substituted; and R 8 represents a leaving group or the like).