The invention provides a curved belt support apparatus (300) that prevents a curved belt (200) from moving inward by supporting a thick part (220) of the curved belt that thickens in both vertical directions at the outer edge of the belt. An upper roller (370) is brought in contact with the upper inside surface (221) of the thick part (220), a lower guide roller (380) is brought in contact with the lower guide roller (380) is brought in contact with the lower inside surface (222) of the thick part (200), and the upper and lower guide rollers are elastically supported such that they can move up and down. When operated, the upper guide roller (370) and the lower guide roller (380) are moved diagonally upward and downward, respectively, in the direction of the radial inner edge of the curved belt so that the thick part (220) of the belt is released from the upper and lower guide rollers.