To provide a polyester composite fiber having a heat-shielding property due to high reflectance in an infrared wavelength range (800 to 3000 nm) easy to be changed into thermal energy, and having color development property comparable to that of conventional polyester fibers. The composite fiber is a core-sheath type composite fiber including a core component and a sheath component of 10: 90 to 30: 70 (mass ratio). The core component includes a thermoplastic polymer including a sunlight shielding material having an average particle size of 0.5 µm or smaller in 8-70 wt%. The sheath component includes a polyester-type polymer including heat-shielding fine particles in 0.5-10 wt%, the heat-shielding fine particles capable of maintaining color development property and having an average particle size of 0.1 µm or smaller which is smaller than that of the sunlight shielding material.