A traveling mode switching controller of a hybrid electric vehicle that has an engine mounted on the vehicle and a drive motor (4, 6) for actuating drive wheels (3, 5) by means of electric power supplied from a drive battery and that travels by switching between a first traveling mode in which the engine is deactivated and the drive motor (4, 6) is activated by means of the electric power supplied from the drive battery to actuate the drive wheels (3, 5) and a second traveling mode in which the engine is actuated and the drive wheels (3, 5) are actuated by means of driving power of the engine or in which a generator connected to the engine is actuated and the drive motor (4, 6) is actuated to actuate the drive wheels (3, 5), the traveling mode switching controller comprising: a state-of-charge detection unit (11 a) for detecting a state of charge of the drive battery; a driver request output detection unit for detecting a driver request output from an operation amount of an accelerator pedal of the vehicle; a correction unit for calculating a vehicle request output by making a correction to the driver request output; and a switching control unit for controlling switching from the first traveling mode to the second traveling mode when the vehicle request output exceeds an output threshold value (Pa) based on the state of charge of the drive battery, wherein the switching control unit sets the output threshold value (Pa) low as the state of charge decreases, thereby changing conditions for switching the first traveling mode to the second traveling mode, characterized in that: the correction unit performs a damping process for decreasing an amount of change in the driver request output to thus calculate the vehicle request output, the correction unit sets low a time constant, which is a rate of decrease of the amount of change in the driver request output to be employed in the damping processing, as the state of charge decreases. a state-of-charge detection unit (11 a) for detecting a state of charge of the drive battery; a driver request output detection unit for detecting a driver request output from an operation amount of an accelerator pedal of the vehicle; a correction unit for calculating a vehicle request output by making a correction to the driver request output; and a switching control unit for controlling switching from the first traveling mode to the second traveling mode when the vehicle request output exceeds an output threshold value (Pa) based on the state of charge of the drive battery, wherein the switching control unit sets the output threshold value (Pa) low as the state of charge decreases, thereby changing conditions for switching the first traveling mode to the second traveling mode, characterized in that: the correction unit performs a damping process for decreasing an amount of change in the driver request output to thus calculate the vehicle request output, the correction unit sets low a time constant, which is a rate of decrease of the amount of change in the driver request output to be employed in the damping processing, as the state of charge decreases. the correction unit performs a damping process for decreasing an amount of change in the driver request output to thus calculate the vehicle request output, the correction unit sets low a time constant, which is a rate of decrease of the amount of change in the driver request output to be employed in the damping processing, as the state of charge decreases.