To obtain the subject compound in high yield without deposition and solidification of tarry matter by reacting an aniline with a diazotizing agent in the coexistence of a water-immiscible organic solvent and hydrochloric acid.

This compound is obtained by reacting (C) an aniline of formula I (X is Cl or Br; Y is O or imino; Z is H, F or Cl; R is a 1-4C alkyl, 3-4C alkenyl or the like) [e.g. 4-chloro-2-fluoro-5-(1-methylethyloxy)aniline) with (D) a diazotizing agent (e.g. nitrous acid) in the coexistence of (A) a water- immiscible organic solvent (e.g. pentane, hexane, petroleum ether or ligroin) and (B) hydrochloric acid pref. at -10 to 20°C for 10 min. to 20 h to yield the aimed compound of formula II. It is preferable that, based on the component C, the amount of the component B to be used is normally 1-10 mol. in terms of hydrogen chloride and the component A to be used is about at ≥0.1 weight time and the component D to be used is about at 1-1.2 molar times.