A polyphenylene ether resin composition obtainable by melt-mixing a polyphenylene ether (A) comprising a structural unit (a) represented by formula (1): (wherein R1 and R2 each independently represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, and the like), and/or a structural unit (b) represented by formula (2): (wherein R3 and R4 each independently represent a hydrogen atom, a halogen atom, an optionally substituted alkyl group, and the like), with a nitrogen compound (B) comprising at least one group selected from the group consisting of primary amino groups, secondary amino groups and tertiary amino groups in a single molecule thereof, wherein the polyphenylene ether (A) comprises 0.1% by mass or more and 1.5% by mass or less of at least one type of aromatic hydrocarbon (C) containing 7 or 8 carbon atoms.