Reading apparatus determining whether a read is valid and image forming apparatus including the reading apparatus

A reading apparatus includes: a conveyor that conveys transfer paper on which an image has been formed by using rotation of a stepping motor; a driver that performs control in such a manner as to supply control pulses to the stepping motor and rotate the stepping motor in predetermined target rotation steps; an encoder that detects the rotation of the stepping motor and obtains detected rotation steps; a reader that reads the image formed on the transfer paper in a state where the transfer paper is being conveyed by the conveyor; and a controller that detects a difference between an ideal value and an actual value of the detected rotation steps in the target rotation steps, and determines, on the basis of the difference, whether a read in the reader is valid or invalid.