A vehicle comprising: an internal combustion engine that supplies drive power to a travel device via power transmission means; a transmission provided to the power transmission means; a shift control unit that adjusts a shift ratio of the transmission; a motor generator connected to the power transmission means; a motor control unit that performs motor assist control for assisting the internal combustion engine by outputting power from the motor generator to the power transmission means; a battery that receives charging power using the motor generator, and provides drive power to the motor generator; a load information generation part that generates load information representing an increase in rotational load received by the internal combustion engine; a motor assist characteristic calculation part that calculates a motor assist characteristic for motor assist control, based on the load information; and a mechanical assist shift ratio calculation part that calculates the shift ratio for the mechanical assist control; wherein the vehicle comprises an assist control determination part that executes the motor assist control, in order to eliminate the increase in rotational load, in priority to mechanical assist control for assisting the internal combustion engine by reducing the shift ratio of the transmission through the shift control unit, characterized in that the internal combustion engine further supplies drive power to a work device via the power transmission means, and in that the motor assist characteristic defines an assist amount and an assist time period of the motor assist control, wherein the motor assist characteristic consists of a start motor assist characteristic area in which a constant assist amount is maintained for a prescribed time period, and an end motor assist characteristic area in which the assist amount is reduced to zero over time. an internal combustion engine that supplies drive power to a travel device via power transmission means; a transmission provided to the power transmission means; a shift control unit that adjusts a shift ratio of the transmission; a motor generator connected to the power transmission means; a motor control unit that performs motor assist control for assisting the internal combustion engine by outputting power from the motor generator to the power transmission means; a battery that receives charging power using the motor generator, and provides drive power to the motor generator; a load information generation part that generates load information representing an increase in rotational load received by the internal combustion engine; a motor assist characteristic calculation part that calculates a motor assist characteristic for motor assist control, based on the load information; and a mechanical assist shift ratio calculation part that calculates the shift ratio for the mechanical assist control; wherein the vehicle comprises an assist control determination part that executes the motor assist control, in order to eliminate the increase in rotational load, in priority to mechanical assist control for assisting the internal combustion engine by reducing the shift ratio of the transmission through the shift control unit, characterized in that the internal combustion engine further supplies drive power to a work device via the power transmission means, and in that the motor assist characteristic defines an assist amount and an assist time period of the motor assist control, wherein the motor assist characteristic consists of a start motor assist characteristic area in which a constant assist amount is maintained for a prescribed time period, and an end motor assist characteristic area in which the assist amount is reduced to zero over time.