A control system comprising: a first storage unit that stores a plurality of pieces of data indicating, in association with each other, a factor that occurs with respect to a vehicle and control contents of the vehicle to be performed with respect to the factor; an estimating unit that estimates the factor and a required time until encountering the factor based on a result of an observation of a periphery of the vehicle, wherein the control system is characterized in further comprising: a second storage unit that can be accessed at a higher speed than the first storage unit, and that stores a smaller number of pieces of data than the number of pieces of data stored in the first storage unit, wherein the second storage unit selectively stores data stored in the first storage unit; and a deciding unit that decides control contents of the vehicle based on the estimated factor and the data, wherein when the estimated required time is longer than a threshold, the deciding unit decides control contents of the vehicle based on data stored in the first storage unit, and when the estimated required time is equal to or shorter than the threshold, the deciding unit decides control contents of the vehicle based on data stored in the second storage unit. a first storage unit that stores a plurality of pieces of data indicating, in association with each other, a factor that occurs with respect to a vehicle and control contents of the vehicle to be performed with respect to the factor; an estimating unit that estimates the factor and a required time until encountering the factor based on a result of an observation of a periphery of the vehicle, wherein the control system is characterized in further comprising: a second storage unit that can be accessed at a higher speed than the first storage unit, and that stores a smaller number of pieces of data than the number of pieces of data stored in the first storage unit, wherein the second storage unit selectively stores data stored in the first storage unit; and a deciding unit that decides control contents of the vehicle based on the estimated factor and the data, wherein when the estimated required time is longer than a threshold, the deciding unit decides control contents of the vehicle based on data stored in the first storage unit, and when the estimated required time is equal to or shorter than the threshold, the deciding unit decides control contents of the vehicle based on data stored in the second storage unit. a second storage unit that can be accessed at a higher speed than the first storage unit, and that stores a smaller number of pieces of data than the number of pieces of data stored in the first storage unit, wherein the second storage unit selectively stores data stored in the first storage unit; and a deciding unit that decides control contents of the vehicle based on the estimated factor and the data, wherein when the estimated required time is longer than a threshold, the deciding unit decides control contents of the vehicle based on data stored in the first storage unit, and when the estimated required time is equal to or shorter than the threshold, the deciding unit decides control contents of the vehicle based on data stored in the second storage unit.