PURPOSE: To provide the subject method for producing goethite particle powder in which the particle powder assuming a spindle form having a uniform particle size and a large axial ratio (major axis diameter/minor axis diameter) without mixing dendritic particles therein is industrially obtained.

CONSTITUTION: An aqueous solution of an alkali carbonate or a mixed aqueous solution of the alkali carbonate with an alkali hydroxide is made to react with an aqueous solution of a ferrous salt to provide a suspension of pH8-10 containing FeCO3-or Fe-containing precipitates. The resultant suspension is then aged in a reducing atmosphere and an oxygen-containing gas is then aerated into the suspension to carry out oxidizing reaction. Thereby, the objective goethite particles assuming a spindle form are produced. In this process, the previous presence of a reducing agent in the solution before aging the liquid containing the FeCO3-or Fe-containing precipitates to afford the goethite particle powder can cause the production of goethite particles having a uniform particle size and a large axial ratio and assuming the spindle form without mixing dendritic particles therein.