To provide a driving force distribution device capable of securing control responsiveness even in cold air.

A driving force distribution device rotatably supports the shaft of a second roller via a bearing in the eccentric hollow hole of a crankshaft rotatable around the fixed axis of a housing, turns a second roller by rotating the crankshaft around the fixed axis, and controls distribution of a driving force between a main driving wheel and a driven wheel by an increasing/decreasing mechanism for increasing/decreasing a diameter-direction pressing force of the second roller to the first roller. When an oil temperature is higher than a predetermined oil temperature, the driving force is distributed by reverse rotation control where the turning direction of the second roller and the rotational direction of the second roller are reverse to each other. When the oil temperature is equal to or lower than the predetermined oil temperature, the driving force is distributed by similar rotation control where the turning direction of the second roller and the rotational direction of the second roller are similar to each other.