To efficiently produce a low-molecular-weight PPO containing hydroxy groups at both terminals.

In the method for producing the polyphenylene oxide having 500-30,000 molecular weight by oxidatively polymerizing a bis(4-hydroxyphenyl)alkane compound in the presence of an enzyme, a 4-hydroxyphenylcarbonyl compound produced as a by-product is reduced to give a 4-hydroxybenzyl alcohol compound. The 4-hydroxybenzyl alcohol compound is reacted with a monohydric phenol compound to give the bis(4-hydroxyphenyl)alkane compound, which is subjected to an oxidation polymerization reaction.