A conveyance apparatus includes a platen having a flat supporting surface that supports a conveyor belt, from its inside, being stretched between first and second rollers. The apparatus further includes an encoder roller disposed between the first roller and the platen so as to be in contact with the conveyor belt from its inside, and a rotary encoder that follows the encoder roller to rotate. The belt is inclined between the first roller and the platen so as to form an obtuse angle with the supporting surface. A contact position between the encoder roller and the belt is in between a first imaginary plane including the supporting surface, and a second imaginary plane spreading through the nearer one, to the first roller, of both ends of the supporting surface in a direction of conveyance by the belt on the supporting surface.