To accurately read optical information more than an opening diameter of a read opening without the read opening contacted with a reading object, in a reader for reading a bar code by irradiating light from a light source to a bar-code label, converging the reflected light through a mirror and a stop by a lens and focusing the converged light on a line image sensor with a shutter, a wavelength detector for detecting a wavelength of the reflected light and a light guide for irradiating light spots indicative of a readable range to the label are provided. Whether a reading state is in a contact reading state in which a read opening contacts the label or in a noncontact reading state in which the read opening separates from the label is determined based on a wavelength of the reflected light detected by the wavelength detector. A light emission quantity and a shutter speed are controlled so as to keep an incident light quantity to the image sensor at an optimum value on a basis of the decided result and reflected light intensity obtained by integrating a line sensor output.