PURPOSE: To provide a trough type roller capable of reducing the radius of the curve of a belt of a curved conveyor.

CONSTITUTION: Upper end parts of a pair of links 5a, 5b are turnably connected to a roller stand 4 to support a center roller 2 and a pair of side rollers 3. The respective links 5a, 5b are inclined outwardly toward the lower end, and the lower end parts of the respective links 5a, 5b are turnably connected to a stand supporting table 6. The elasticity of an elastic member 8 is provided to the roller stand 4 to make the center roller 2 in the horizontal condition. When a belt 1 is moved toward the inside of the curve by the change of the tension of the belt 1 to be supported by the center roller 2 and a pair of side rollers 3, the roller stand 4 is swayed to the belt moving side due to the centripetal force by the belt tension to prevent the falling out of the belt 1.