In an apparatus for reading a data storage medium, a control unit controls a first driving unit so as to enable the first driving unit to drive a carrier frame loaded with the data storage medium thereon to move back and forth between first and second limit positions along a first direction, receives optically detectable information read by an optical detecting unit from the data storage medium, and activates a second driving unit to move the optical detecting unit by a predetermined distance along a second direction transverse to the first direction upon detection that the carrier frame has been moved by the first driving unit from one of the first and second limit positions to the other one of the first and second limit positions.