An original reading apparatus includes: a reading unit configured to read an original placed on a platen while moving in a predetermined direction in a housing; a sensor provided in the housing and configured to detect presence of the original in a predetermined position on the platen to identify a size of the original; a holding member movable in the housing and configured to hold the sensor and a cable extending from the sensor; and a cover configured to cover a predetermined space on a rear side of the platen mounted to the housing. A grip portion used by an operator to move the holding member is provided at one end of the holding member extending to the predetermined space through an opening portion in a wall on a rear side of the housing. When the cover is removed, the operator is allowed to grip the grip portion.