To cullow a lubricating oil supply device for an on-vehicle refrigerator mounted to an automobile to supply oil to an oil pump for its lubrication until the inclined angle of an uphill or downhill road comes up to the maximum ascending descending angle of 30° for the automobile when the automobile goes up or down over the uphill or downhill road.

In an oil supply device to be used for an on-vehicle refrigerator using an automobile engine as a driving source, the depth of an oil basin 1 supplying oil to an oil pump, is made deep, an oil suction port 4 is set up at the center position of its bottom part, and the device is so designed that a ratio of depth to length in the automobile running direction is set up in such a way that the oil suction port 4 will never be exposed out of oil 6 with the limit of the inclination of the automobile inclined to the maximum uphill/ downhill angle of 30° when the filling quantity of oil is 30%.