Method for producing high-purity terephthalic acid

A method for producing high-purity terephthalic acid, comprising following steps (a) to (c) : the step (a) ; obtaining crude terephthalic acid crystal by liquid phase-oxidizing a p-phenylene compound; the step (b) ; obtaining a terephthalic acid crystal slurry by a catalytic hydrogenation treatment of the crude terephthalic acid crystal; and the step (c) ; introducing the terephthalic acid crystal slurry into an upper portion of a mother liquor replacement tower, and bringing the slurry into contact with an upward flow of replacement water introduced from a bottom portion of the mother liquor replacement tower while making the terephthalic acid crystal settled down in the tower, and extracting the terephthalic acid crystal as a slurry with the replacement water from the tower bottom portion, wherein (1) a stirring blade unit is disposed in a slurry layer in the bottom portion of the mother liquor replacement tower, and fluidity of the slurry layer is maintained by rotating the stirring blade unit in such a way that stirring power is 0.1 to 1.0 kWh/m 3 per unit volume of the slurry layer, and (2) the replacement water is fed through the replacement water feed opening provided in the stirring blade unit.