A conveyor conveys a sheet along a conveyance path provided with an ultrasonic sensor, and includes: an updating member that successively updates a parameter indicating aged deterioration of the conveyor; a searcher that searches a look-up table storing pieces of noise data of noises predicted to be superimposed on a detection signal of the ultrasonic sensor in accordance with a degree of the aged deterioration, and obtains a piece of noise data corresponding to a current parameter value of the conveyor; and a signal processor that uses, for signal processing, a remaining portion of the detection signal of the ultrasonic sensor excluding a portion corresponding to the piece of noise data obtained by the searcher.