This method for a manufacturing a 1,1-disubstituted hydrazine compound represented by a formula (II) involves reacting a hydrazino compound represented by a formula (I) with a compound represented by a formula: R-Hal in an aprotic polar solvent in the presence of a base selected from an alkali metal hydroxide and alkaline-earth metal hydroxide in an amount of 1.0 to 3.0 equivalents based on the hydrazino compound. In the formulae, X represents an oxygen atom, a sulfur atom, —CH2— or the like, and each of RX represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 6 carbon atoms, a cyano group, a nitro group, a fluoroalkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms or the like. An arbitrary C—RX that forms the ring is optionally substituted with a nitrogen atom. Hal represents a chlorine atom, a bromine atom, or an iodine atom, and R represents a substituted or unsubstituted organic group having 1 to 12 carbon atoms.