A differential gear mechanism for motor vehicles, which is effective as well as quite simple construction-wise and low in production cost, comprises a differential gear case made rotatively rigid with a ring gear, a tubular body mounted within the case with a predetermined amount of angular backlash and being rotated thereby, two coaxially aligned sleeves attached to the ends of respective axle shafts and fitting rotatably within the tubular body, and for each sleeve, two freewheel devices arranged to alternately act between the tubular body and the sleeve and a change-over mechanism for activating either of the freewheel devices according to the running direction, in forward or reverse gear.