A drive control system in a series-hybrid utility vehicle comprises a motor for driving a wheel; a battery; an engine electric generator for generating the electric power charged into the battery; and a controller configured to estimate an SOC value of the battery, and control the motor and the engine electric generator in accordance with an HV mode or an EV mode; wherein when the estimated SOC value is less than a predetermined low threshold, the controller stops electric power supply from the battery to the motor; and when the estimated SOC value is less than a predetermined medium threshold greater than the predetermined low threshold, the controller sets the HV mode, and controls the motor and the engine electric generator such that a driving power of the motor is suppressed in a state where the motor is supplied with the electric power from the battery.