An automotive arithmetic device mounted on a motor vehicle, the automotive arithmetic device comprising: a vehicle external environment estimation unit that estimates a vehicle external environment using deep learning based on an output from an information acquisition device (50, 51) that acquires information of the vehicle external environment; a first route calculation unit that calculates a first candidate route based on an estimation result of the vehicle external environment estimation unit; a target object recognition unit that recognizes a target object outside the motor vehicle based on the output from the information acquisition device (50, 51) according to a predetermined rule; a static safe area setting unit that sets a static safe area which is an area where the target object is avoidable based on a recognition result of the target object recognition unit; and a target motion determination unit that receives outputs from the first route calculation unit and the static safe area setting unit and determines a target motion of the motor vehicle, wherein the target motion determination unit selects the first candidate route as a route that the motor vehicle should take and determines the target motion of the motor vehicle so that the motor vehicle takes the first candidate route, characterized in that the target object outside the motor vehicle is recognized without using deep learning, the first candidate route is taken when it is entirely within the static safe area, and the target motion determination unit does not select the first candidate route as the route that the motor vehicle should take when the first candidate route at least partially deviates from the static safe area. a vehicle external environment estimation unit that estimates a vehicle external environment using deep learning based on an output from an information acquisition device (50, 51) that acquires information of the vehicle external environment; a first route calculation unit that calculates a first candidate route based on an estimation result of the vehicle external environment estimation unit; a target object recognition unit that recognizes a target object outside the motor vehicle based on the output from the information acquisition device (50, 51) according to a predetermined rule; a static safe area setting unit that sets a static safe area which is an area where the target object is avoidable based on a recognition result of the target object recognition unit; and a target motion determination unit that receives outputs from the first route calculation unit and the static safe area setting unit and determines a target motion of the motor vehicle, wherein the target motion determination unit selects the first candidate route as a route that the motor vehicle should take and determines the target motion of the motor vehicle so that the motor vehicle takes the first candidate route, characterized in that the target object outside the motor vehicle is recognized without using deep learning, the first candidate route is taken when it is entirely within the static safe area, and the target motion determination unit does not select the first candidate route as the route that the motor vehicle should take when the first candidate route at least partially deviates from the static safe area.