A method for manufacturing an isocyanate compound represented by formula (2) (2) wherein R1 represents a methyl group, an ethyl group, a cyclopropyl group, a chlorine atom, a bromine atom, or a methoxy group; and R2 represents an alkyl group having 1 to 6 carbon atoms, comprising reacting an aniline compound represented by formula (1) (1) wherein R1 and R2 are defined as above with a phosgene compound at a temperature of from 40° C. to the boiling point of the inert solvent in at least one kind of inert solvent.