A resin composition comprising: (a) (a-1) a polyphenylene ether resin or a mixed resin of (a-1) a polyphenylene ether resin and (a-2) a styrene resin; (b) a hydrogenated block copolymer; (c) a phosphoric acid ester compound; and (d) at least one selected from the group consisting of a phosphinic acid salt represented by general formula, shown below, a diphosphinic acid salt represented by general formula, shown below, and a condensate thereof, where, in general formulae and, R 1 and R 2 are each, independently of one another, a linear or branched alkyl group having a carbon number of 1 to 6 or an aryl group having a carbon number of 6 to 10, R 3 is one selected from the group consisting of a linear or branched alkylene group having a carbon number of 1 to 10, an arylene group having a carbon number of 6 to 10, an alkylarylene group having a carbon number of 6 to 10, and an arylalkylene group having a carbon number of 6 to 10, M is at least one selected from the group consisting of a calcium ion, a magnesium ion, an aluminum ion, a zinc ion, a bismuth ion, a manganese ion, a sodium ion, a potassium ion, and a cationized nitrogenous base, and m is an integer of 1 to 3, n is an integer of 1 to 3, x is 1 or 2, and 2n = mx, wherein relative to 100 parts by mass, in total, of the (a) component and the (b) component: the (a) component is 50 parts by mass to 80 parts by mass; the (b) component is 20 parts by mass to 50 parts by mass; and the (c) component and the (d) component are 17 parts by mass to 40 parts by mass, in total, a mass ratio (c)/(d) of the (c) component and the (d) component is 5/95 to 30/70, the (a-1) polyphenylene ether resin is 40 mass% to 80 mass% and the (a-2) styrene resin is 20 mass% to 60 mass% in 100 mass% of the mixed resin of the (a-1) polyphenylene ether resin and the (a-2) styrene resin, and a phase that contains the (a) component forms a continuous phase. (a) (a-1) a polyphenylene ether resin or a mixed resin of (a-1) a polyphenylene ether resin and (a-2) a styrene resin; (b) a hydrogenated block copolymer; (c) a phosphoric acid ester compound; and (d) at least one selected from the group consisting of a phosphinic acid salt represented by general formula, shown below, a diphosphinic acid salt represented by general formula, shown below, and a condensate thereof, R 1 and R 2 are each, independently of one another, a linear or branched alkyl group having a carbon number of 1 to 6 or an aryl group having a carbon number of 6 to 10, R 3 is one selected from the group consisting of a linear or branched alkylene group having a carbon number of 1 to 10, an arylene group having a carbon number of 6 to 10, an alkylarylene group having a carbon number of 6 to 10, and an arylalkylene group having a carbon number of 6 to 10, M is at least one selected from the group consisting of a calcium ion, a magnesium ion, an aluminum ion, a zinc ion, a bismuth ion, a manganese ion, a sodium ion, a potassium ion, and a cationized nitrogenous base, and m is an integer of 1 to 3, n is an integer of 1 to 3, x is 1 or 2, and 2n = mx, wherein relative to 100 parts by mass, in total, of the (a) component and the (b) component: the (a) component is 50 parts by mass to 80 parts by mass; the (b) component is 20 parts by mass to 50 parts by mass; and the (c) component and the (d) component are 17 parts by mass to 40 parts by mass, in total, a mass ratio (c)/(d) of the (c) component and the (d) component is 5/95 to 30/70, the (a-1) polyphenylene ether resin is 40 mass% to 80 mass% and the (a-2) styrene resin is 20 mass% to 60 mass% in 100 mass% of the mixed resin of the (a-1) polyphenylene ether resin and the (a-2) styrene resin, and a phase that contains the (a) component forms a continuous phase. the (a) component is 50 parts by mass to 80 parts by mass; the (b) component is 20 parts by mass to 50 parts by mass; and the (c) component and the (d) component are 17 parts by mass to 40 parts by mass, in total, a mass ratio (c)/(d) of the (c) component and the (d) component is 5/95 to 30/70, the (a-1) polyphenylene ether resin is 40 mass% to 80 mass% and the (a-2) styrene resin is 20 mass% to 60 mass% in 100 mass% of the mixed resin of the (a-1) polyphenylene ether resin and the (a-2) styrene resin, and a phase that contains the (a) component forms a continuous phase.