To aim at the improvement of melt viscosity of a thermoplastic polyester resin composition and the betterment of transparency and luster of a molded article.

This resin composition contains (B) 0.1-50 pts.wt. thickening agent and (C) 0.1-30 pts.wt. another thickening agent based on (A) 100 pts.wt. thermoplastic polyester resin, wherein, (B) the thickening agent is provided by having ≥60°C glass transition temperature and 50-500 μm volume-average particle diameter, and covering (B-1) 100 pts.wt. polymer particles without having reactivity with the thermoplastic polyester resin by (B-2) 0.5-30 pts.wt. polymer particles having 0.01-0.5 μm volume-average particle diameter, and (C) the other thickening agent is provided by having ≥60°C glass transition temperature and 50-500 μm volume-average particle diameter, and covering (C-1) 100 pts.wt. polymer particles without having reactivity with the thermoplastic polyester resin by (C-2) 0.5-30 pts.wt. polymer particles having 0.01-0.5 μm volume-average particle diameter. The molded article of the same is also provided.