1. A 2-dimensional code reader comprising: means for sensing an image including a 2-dimensional code therein by scanning the image; means for amplifying signals fed from the sensing means; means for identifying a code-region where the 2-dimensional code exists in the image, said code region being defined by symbol marks; and means for setting an amplifying rate of the amplifying means so that a signal level of the code-region falls within a predetermined control range.