To efficiently obtain the subject aqueous dispersion having a large aspect ratio and useful for processing fibers, etc., by polymerizing tetrafluoroethylene in the presence of a specific fluorinecontaining polymer acting as a surfactant.

This method for producing (D) an aqueous dispersion containing polytetrafluoroethylene particles having an aspect ratio of ≥2 comprises polymerizing (C) tetrafluoroethylene in the presence of (A) a polymer comprising polymer units of formula I (Rf is a 1-6C perfluoroalkylene; M is an alkali metal ion or ammonium ion) or (B) a copolymer comprising the polymer units of formula I and polymer units of formula II (X is F atom or Cl atom). The polymer units of formula I in the component B is ≥40 mol.% based on the total polymer units. The mol.wt. of the component A or B is preferably 2,000-100,000. The component A or B is preferably used in an amount of 0.03-0.5 wt.% based on water used as the aqueous medium.