An image reader adopting an off-axial optical system, an adjustable imaging mirror and a CCD fixed to a highly rigid structure. Since the relative position between reflecting and imaging mirrors can be set highly accurately, adjusting only the CCD-mounting position allows a required specification of the read image to be met. The imaging mirror can easily be adjusted without distorting the reflecting surface. The reflecting and imaging mirrors, and the CCD-mounting-position adjuster are positioned directly to reflecting-mirror supporting sections, imaging-mirror supporting sections, and CCD supporting sections, which are integrated with a carriage casing, and fixed to them. The CCD is fixed to the carriage casing with the CCD-mounting-position adjuster. An imaging mirror close to a diaphragm and adjacent to the image is supported by a mirror adjusting plate, which can be displaced to adjust the position of the imaging mirror.