An image reader apparatus includes: an image pickup device which is controllably exposed to an object to produce an image signal of the object; a mover which moves the object and the image pickup device relative to each other; a storage operable to store an image signal; a writing device which is operable to write an image signal in the storage; a reading device which is operable to read an image signal from the storage; a discriminator which discriminates whether one of the writing device and the reading device is in operation; and a controller which controls the exposure of the image pickup device in accordance with a result of the discriminator.