Fiber-reinforced resin composition, and fiber-reinforced composite material

A fiber-reinforced resin composition comprising a polyarylene sulfide (A), a carbodiimide compound (B) and carbon fibers (C) surface-treated with a sizing agent (D), wherein the carbodiimide compound (B) is an aliphatic carbodiimide compound, the sizing agent (D) is a compound having, in one molecule, three or more functional groups of at least one type selected from the group consisting of a carboxyl group and an amino group, the fiber-reinforced resin composition contains 0.1 to 10 parts by mass of the component (B) and 10 to 300 parts by mass of the component (C) based on 100 parts by mass of the component (A), and 0.01 to 5 parts by mass of the component (D) based on 100 parts by mass of the component (C), and

• the sulfur concentration ratio S/C measured by energy dispersive X-ray spectroscopy (EDX) satisfies formula (1):
• 10(%)≤ΔS=(S2−S1)/S2×100≤70(%) (1)
• wherein ΔS represents a gradient of the sulfur element concentration viewed at a cross section orthogonal to an axis center direction of the component (C), S1 represents a sulfur concentration ratio S/C in a region (T1) remaining after excluding the component (C) from inside of a circle drawn at a distance of 500 nm in a normal direction outward from the cross-sectional circle of the component (C), and S2 represents a sulfur concentration ratio S/C in a region (T2) remaining after excluding the component (C) and the region (T1) from the inside of the circle drawn at a distance of 500 nm in the normal direction outward from the region (T1).