A polyphenylene ether resin composition includes (A) polyphenylene ether, and (B) a block copolymer including a butadiene block having a molar ratio of a 1,2-bonding structure to a 1,4-bonding structure of 80:20 to 100:0 and a styrene block. The number average molecular weight (Mn) of the component (A) may be 1,000 to 7,000, the weight ratio of the styrene block to the butadiene block in the component (B) may be 10:90 to 80:20, and the weight average molecular weight (Mw) of the component (B) may be 2,000 to 100,000.