DATA SYMBOL READER WITH AN OBSERVATION WINDOW

A data symbol reader for reading a data symbol formed on a reading surface which includes: a head portion which is placed on the reading surface to cover the data symbol when reading the data symbol; an image pick-up device on which an image of the data symbol is to be formed; and an image-forming optical system for leading light reflected on the data symbol to the image pick-up device to form the image of the data symbol on the image pick-up device. The head portion includes an enclosing portion for enclosing the data symbol while an open end of the enclosing portion contacts the reading surface. The enclosing portion includes a light transmissive member through which the inside of the enclosing portion is visible from the outside of the enclosing portion. The light transmissive member is inclined by a predetermined angle with respect to an optical axis of the image-forming optical system.