A flat metal aligning device (21) which allows the flat metal entering a rolling stand (22) of a rolling mill to be effectively aligned or centered by using retractable pusher elements to control the alignment and feeding of metal work pieces into the rolling stand, thus avoiding potential damage to the working rollers (2) while reducing the times to produce the rolled products. Moreover, the device according to the invention allows the rolling stand to be supplied with short slabs when they may not be fed by the motorized rollers at the stand inlet, precisely due to their short length.