A flame retardant composition, comprising: 20 to 50 parts by mass of the following component; 50 to 80 parts by mass of the following component (with a proviso that the total amount of said components and is 100 parts by mass); and 0.5 to 15 parts by mass of the following component: Component: a (poly)phosphate compound represented by the following Formula Component: a (poly)phosphate compound represented by the following Formula Component: a polyhydric alcohol compound, wherein Component is dipentaerythritol, or is 1,3,5-tris(2-hydroxyethyl)isocyanurate and/or sorbitol (wherein, n represents a number of 1 to 100; X 1 represents ammonia or a triazine derivative represented by the following Formula; and 0 < p ≤ n + 2) (wherein, Z 1 and Z 2 each independently represent a group selected from the group consisting of a -NR 5 R 6 group [wherein, R 5 and R 6 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms or a methylol group], a hydroxy group, a mercapto group, a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched alkoxy group having 1 to 10 carbon atoms, a phenyl group and a vinyl group) (wherein, r represents a number of 1 to 100; Y 1 represents [R 1 R 2 N(CH 2) m NR 3 R 4], piperazine or a piperazine ring-containing diamine; R 1, R 2, R 3 and R 4 each represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, which R 1, R 2, R 3 and R 4 may be the same group or different groups; m represents an integer of 1 to 10; and 0 < q ≤ r + 2). 20 to 50 parts by mass of the following component; 50 to 80 parts by mass of the following component (with a proviso that the total amount of said components and is 100 parts by mass); and 0.5 to 15 parts by mass of the following component: Component: a (poly)phosphate compound represented by the following Formula Component: a (poly)phosphate compound represented by the following Formula Component: a polyhydric alcohol compound, wherein Component is dipentaerythritol, or is 1,3,5-tris(2-hydroxyethyl)isocyanurate and/or sorbitol (wherein, n represents a number of 1 to 100; X 1 represents ammonia or a triazine derivative represented by the following Formula; and 0 < p ≤ n + 2) (wherein, Z 1 and Z 2 each independently represent a group selected from the group consisting of a -NR 5 R 6 group [wherein, R 5 and R 6 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms or a methylol group], a hydroxy group, a mercapto group, a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched alkoxy group having 1 to 10 carbon atoms, a phenyl group and a vinyl group) (wherein, r represents a number of 1 to 100; Y 1 represents [R 1 R 2 N(CH 2) m NR 3 R 4], piperazine or a piperazine ring-containing diamine; R 1, R 2, R 3 and R 4 each represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, which R 1, R 2, R 3 and R 4 may be the same group or different groups; m represents an integer of 1 to 10; and 0 < q ≤ r + 2). Component: a (poly)phosphate compound represented by the following Formula Component: a (poly)phosphate compound represented by the following Formula Component: a polyhydric alcohol compound, wherein Component is dipentaerythritol, or is 1,3,5-tris(2-hydroxyethyl)isocyanurate and/or sorbitol (wherein, n represents a number of 1 to 100; X 1 represents ammonia or a triazine derivative represented by the following Formula; and 0 < p ≤ n + 2) (wherein, Z 1 and Z 2 each independently represent a group selected from the group consisting of a -NR 5 R 6 group [wherein, R 5 and R 6 each independently represent a hydrogen atom, a linear or branched alkyl group having 1 to 6 carbon atoms or a methylol group], a hydroxy group, a mercapto group, a linear or branched alkyl group having 1 to 10 carbon atoms, a linear or branched alkoxy group having 1 to 10 carbon atoms, a phenyl group and a vinyl group) (wherein, r represents a number of 1 to 100; Y 1 represents [R 1 R 2 N(CH 2) m NR 3 R 4], piperazine or a piperazine ring-containing diamine; R 1, R 2, R 3 and R 4 each represent a hydrogen atom or a linear or branched alkyl group having 1 to 5 carbon atoms, which R 1, R 2, R 3 and R 4 may be the same group or different groups; m represents an integer of 1 to 10; and 0 < q ≤ r + 2).