This invention relates to a polyarylene sulfide oxide of which crystallization degree is 10% or higher by wide-angle X-ray diffraction measurement and a heat of fusion is 15 J/g or less by differential scanning calorimeter (DSC) measurements, and a production method of the same. There is provided a polyarylene sulfide oxide that excels in heat resistance, chemical resistance and moisture absorption resistance, and a production method of the same.
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