A polyphenylene ether resin composition comprising: a polyphenylene ether; and a condensed metal phosphate, wherein when a bend elastic constant of the polyphenylene ether resin composition before aging measured in accordance with ISO-178 in an atmospheric air is taken as 100%, time required for obtaining a bend elastic constant of 115% or more through aging in which the polyphenylene ether resin composition is left at rest at 150°C is 2,000 hours or more; a shaped article of 12.6 cm in length, 1.3 cm in width, and 1.6 mm in thickness formed from the polyphenylene ether resin composition exhibits a rate of change in chloroform-insoluble content of 15 mass% or less before and after aging in which the shaped article is left at rest for 1,000 hours at 150°C; and the polyphenylene ether includes at least one structural unit selected from a group consisting of chemical formulate, and illustrated below; wherein X 1 in the chemical formulae and is a group selected from chemical formulae illustrated below, where R 1 and R 2 in X 1 are each, independently of one another, a substituent having a carbon number of 1 or more, wherein X 2 in chemical formula is a group selected from chemical formulae illustrated below, where R 3 and R 4 in X 2 are each, independently of one another, a group selected from a group consisting of a hydrogen atom, an alkyl group, an aryl group, an aminoalkyl group, and an arylamino group, and R 3 and R 4 may form a cyclic structure through bonding of carbon atoms included therein, with the proviso that chemical formula does not substantially include a carbon-carbon double bond other than an aromatic ring double bond. a polyphenylene ether; and a condensed metal phosphate, wherein when a bend elastic constant of the polyphenylene ether resin composition before aging measured in accordance with ISO-178 in an atmospheric air is taken as 100%, time required for obtaining a bend elastic constant of 115% or more through aging in which the polyphenylene ether resin composition is left at rest at 150°C is 2,000 hours or more; a shaped article of 12.6 cm in length, 1.3 cm in width, and 1.6 mm in thickness formed from the polyphenylene ether resin composition exhibits a rate of change in chloroform-insoluble content of 15 mass% or less before and after aging in which the shaped article is left at rest for 1,000 hours at 150°C; and the polyphenylene ether includes at least one structural unit selected from a group consisting of chemical formulate, and illustrated below; wherein X 1 in the chemical formulae and is a group selected from chemical formulae illustrated below, where R 1 and R 2 in X 1 are each, independently of one another, a substituent having a carbon number of 1 or more, wherein X 2 in chemical formula is a group selected from chemical formulae illustrated below, where R 3 and R 4 in X 2 are each, independently of one another, a group selected from a group consisting of a hydrogen atom, an alkyl group, an aryl group, an aminoalkyl group, and an arylamino group, and R 3 and R 4 may form a cyclic structure through bonding of carbon atoms included therein, with the proviso that chemical formula does not substantially include a carbon-carbon double bond other than an aromatic ring double bond. when a bend elastic constant of the polyphenylene ether resin composition before aging measured in accordance with ISO-178 in an atmospheric air is taken as 100%, time required for obtaining a bend elastic constant of 115% or more through aging in which the polyphenylene ether resin composition is left at rest at 150°C is 2,000 hours or more; a shaped article of 12.6 cm in length, 1.3 cm in width, and 1.6 mm in thickness formed from the polyphenylene ether resin composition exhibits a rate of change in chloroform-insoluble content of 15 mass% or less before and after aging in which the shaped article is left at rest for 1,000 hours at 150°C; and the polyphenylene ether includes at least one structural unit selected from a group consisting of chemical formulate, and illustrated below; wherein X 1 in the chemical formulae and is a group selected from chemical formulae illustrated below, where R 1 and R 2 in X 1 are each, independently of one another, a substituent having a carbon number of 1 or more, wherein X 2 in chemical formula is a group selected from chemical formulae illustrated below, where R 3 and R 4 in X 2 are each, independently of one another, a group selected from a group consisting of a hydrogen atom, an alkyl group, an aryl group, an aminoalkyl group, and an arylamino group, and R 3 and R 4 may form a cyclic structure through bonding of carbon atoms included therein, with the proviso that chemical formula does not substantially include a carbon-carbon double bond other than an aromatic ring double bond.