TECHNOLOGY FOCUS - POLYMERS - Preferred Composition: The repeating units derived from methacrylate monomer (1), repeating units derived from vinyl aromatic monomer (2), repeating units derived from methacrylate monomer having aromatic group (3), and cyclic-anhydride repeating units (4 or 5) is 10-70 weight%, 5-40 weight%, 0.1-5 weight% and 20-50 weight%, respectively. The molar ratio of content of repeating unit derived from vinyl aromatic monomer and content of cyclic-anhydride repeating unit is 1-10. Preferred Components: The repeating unit derived from a methacrylate monomer is repeating unit derived from methyl-methacrylate. The repeating unit derived from vinyl aromatic monomer is repeating unit derived from styrene. The repeating unit derived from methacrylate monomer having aromatic group is repeating unit derived from benzyl methacrylate. The cyclic-anhydride repeating unit is repeating unit derived from maleic acid anhydride. Preferred Properties: The acrylic-type thermoplastic resin has weight average molecular weight of 10000-400000 measured using gas phase chromatography, and molecular weight distribution of 1.8-3.0. The absolute value of photoelastic coefficient of acrylic-type thermoplastic resin is less than 3.0x 10-12 Pa-1. The absolute value of the phase difference (Re) of acrylic type thermoplastic resin in surface direction is 30 nm or less. The absolute value of the phase difference (Rth) of the acrylic type thermoplastic resin in thickness direction is 30 nm or less. The ratio (Rth/Re) of the phase difference (Re) of surface direction and the phase difference (Rth) of the thickness direction is more than 0.1 to less than 1. The acrylic-type thermoplastic resin has glass transition temperature (Tg) of 120 degrees C and total-light transmittance of 85% or more. The approximation linear relational expression of birefringence ((DELTA)n(S)) while stretching, and draw ratio (S), and value of inclination (K) satisfies the relation: (DELTA)n(S)=KasteriskS+C. The absolute value of inclination is less than 0.30x 10-6. Preferred Process: The molding product comprises acrylic-type thermoplastic resin. The optical film is obtained by extrusion molding or cast molding acrylic-type thermoplastic resin, and stretching in axial direction such that the draw ratio is 0.1 to 300%. EXAMPLE - Methyl methacrylate (in g) (518), styrene (48), benzyl methacrylate (9.6), maleic acid anhydride (384), methyl isobutyl ketone (240) and n-octylmercaptan (1.2) were mixed. Then, methyl isobutyl ketone (12.96) solution of 2,2'-azobis(isobutyronitrile) was added to the reaction mixture, to obtain thermoplastic resin. The acrylic-type thermoplastic resin had excellent optical characteristics.