Crystals of paroxetine hydrochloride 1/2-hydrate are allowed to separate out by adding water to a solution or suspension comprising paroxetine hydrochloride and a polar organic solvent which contains no water or at most 60% by weight of water to adjust the water content to at least 70% by weight when crystals of paroxetine hydrochloride 1/2-hydrate are allowed to separate out in a water-containing polar organic solvent. Crystals of paroxetine hydrochloride 1/2-hydrate being not colored in pink can be allowed to separate out in the presence of hydrogen chloride when crystals of paroxetine hydrochloride 1/2-hydrate are allowed to separate out in water or a water-containing polar organic solvent.