A thermoplastic resin composition comprising: a (meth)acrylic acid ester copolymer (A) obtained by polymerizing a vinyl monomer mixture (m1) containing a (meth) acrylic acid ester monomer and an aromatic vinyl monomer; a hindered amine compound (C) having a molecular weight of 200 to 1800; and an ultraviolet absorber compound (D) having a maximum absorption wavelength at 250 to 300 nm, as measured according to the method of the description wherein: the thermoplastic resin composition optionally includes a graft copolymer (B) obtained by graft-polymerizing a vinyl monomer mixture (m2) in the presence of a rubber polymer (b1), the (meth)acrylic acid ester monomer is present in an amount of 50 % by mass or more and less than 80 % by mass, and the aromatic vinyl monomer is present in an amount of 12 to 39 % by mass, each based on a total mass of the vinyl monomer mixture (m1), and the hindered amine compound (C) is present in an amount of 0.4 to 1.8 parts by mass, the ultraviolet absorber compound (D) is present in an amount of 0.1 to 1.6 parts by mass, and a sum of the amounts of the hindered amine compound (C) and the ultraviolet absorber compound (D) is not more than 2.0 parts by mass, each relative to 100 parts by mass of a combination of the (meth)acrylic acid ester copolymer (A) and the graft copolymer (B). a (meth)acrylic acid ester copolymer (A) obtained by polymerizing a vinyl monomer mixture (m1) containing a (meth) acrylic acid ester monomer and an aromatic vinyl monomer; a hindered amine compound (C) having a molecular weight of 200 to 1800; and an ultraviolet absorber compound (D) having a maximum absorption wavelength at 250 to 300 nm, as measured according to the method of the description wherein: the thermoplastic resin composition optionally includes a graft copolymer (B) obtained by graft-polymerizing a vinyl monomer mixture (m2) in the presence of a rubber polymer (b1), the (meth)acrylic acid ester monomer is present in an amount of 50 % by mass or more and less than 80 % by mass, and the aromatic vinyl monomer is present in an amount of 12 to 39 % by mass, each based on a total mass of the vinyl monomer mixture (m1), and the hindered amine compound (C) is present in an amount of 0.4 to 1.8 parts by mass, the ultraviolet absorber compound (D) is present in an amount of 0.1 to 1.6 parts by mass, and a sum of the amounts of the hindered amine compound (C) and the ultraviolet absorber compound (D) is not more than 2.0 parts by mass, each relative to 100 parts by mass of a combination of the (meth)acrylic acid ester copolymer (A) and the graft copolymer (B). the thermoplastic resin composition optionally includes a graft copolymer (B) obtained by graft-polymerizing a vinyl monomer mixture (m2) in the presence of a rubber polymer (b1), the (meth)acrylic acid ester monomer is present in an amount of 50 % by mass or more and less than 80 % by mass, and the aromatic vinyl monomer is present in an amount of 12 to 39 % by mass, each based on a total mass of the vinyl monomer mixture (m1), and the hindered amine compound (C) is present in an amount of 0.4 to 1.8 parts by mass, the ultraviolet absorber compound (D) is present in an amount of 0.1 to 1.6 parts by mass, and a sum of the amounts of the hindered amine compound (C) and the ultraviolet absorber compound (D) is not more than 2.0 parts by mass, each relative to 100 parts by mass of a combination of the (meth)acrylic acid ester copolymer (A) and the graft copolymer (B). <EOS>