If the user specifies a color mode, an image reader previously moves a read head to a position where a first read target position r and a read start position on an original are identical with each other. If the user specifies a monochrome mode, the image reader previously moves the read head to a position where a second read target position and the read start position on an original are identical with each other. After this, an image can be read from the same range without increasing the time required for image read processing.