A vehicle driving system includes a slip detector that detects an occurrence of excess slipping; an additive/subtractive slip point calculator that time-discretely calculates an additive/subtractive slip point, which is an additive slip point or a subtractive slip point, on the basis detection or non-detection of an occurrence of excess slipping; a cumulative slip point calculator that sequentially calculates a cumulative slip point that is a cumulative sum of values of the additive/subtractive slip point; and a driving mode switcher that switches between a two-wheel driving mode and an all-wheel driving mode on the basis of the cumulative slip point. When excess slipping is detected, the additive/subtractive slip point calculator calculates the additive slip point on the basis of a driving force correlation value that correlates to a driving force a driving wheel for which the excess slipping has occurred.