Disclosed is an image reading apparatus capable of selectively executing a flow-scan reading method in which a document is read while the document is transported in a state in which a reader is fixed at a predetermined location, and a fixed reading method in which a document is read while the reader is moved in a predetermined direction in a state in which the document is held fixed, the apparatus having a first holding member for holding a document at the predetermined location for implementation of the flow-scan reading method, and a second holding member, which has a spectral transmittance different from that of the first holding member, for holding a document for implementation of the fixed reading method. The apparatus discriminates whether the flow-scan or fixed reading method is executed and sets coefficients, which are used in at least the reader or the image processing unit, in accordance with the flow-scan or fixed reading method. Using the set coefficients, a document is read by the reader and processing is applied to the image signal obtained by reading the document.