An apparatus for controlling operation of a walk-behind electric lawn mower equipped with, a frame configured to be movable over a lawn growth area by a user by hand from behind; an electric motor mounted on the frame; a blade cutter provided at an underneath surface of the frame to be connected to the electric motor and configured to cut grass on the lawn growth area when driven by the electric motor; a rechargeable battery mounted on the frame to be connected to the electric motor and configured to discharge electric power so as to applied to the electric motor as operating electric power and to be charged by a regenerative electric current that is generated by the electric motor during regenerative braking of rotation of the blade cutter; and a motor driver circuit configured to adjust supply of the operating electric power to the electric motor: wherein the apparatus includes: a control unit configured to control operation of the motor driver circuit; a first switching element disposed in a current path of the motor driver circuit connecting the rechargeable battery and the electric motor to allow passage of charge current from the electric motor to the rechargeable battery when turned ON and block the passage of the charging current when turned OFF; a resistor interposed in the current path; a second switching element interposed in the current path in series with the resistor to allow the passage of the charge current from the electric motor to the resistor when turned ON and block the passage of the charge current when turned OFF; and an internal circuit voltage detector configured to produce an output indicating an internal voltage of the motor driver circuit; characterized by: a rechargeable battery temperature detector configured to produce an output indicating a temperature of the rechargeable battery;_ wherein the control unit is configured to control ON/OFF of the first and second switching elements based on the outputs of the rechargeable battery temperature detector and the internal circuit voltage detector. a control unit configured to control operation of the motor driver circuit; a first switching element disposed in a current path of the motor driver circuit connecting the rechargeable battery and the electric motor to allow passage of charge current from the electric motor to the rechargeable battery when turned ON and block the passage of the charging current when turned OFF; a resistor interposed in the current path; a second switching element interposed in the current path in series with the resistor to allow the passage of the charge current from the electric motor to the resistor when turned ON and block the passage of the charge current when turned OFF; and an internal circuit voltage detector configured to produce an output indicating an internal voltage of the motor driver circuit; characterized by: a rechargeable battery temperature detector configured to produce an output indicating a temperature of the rechargeable battery;_ wherein the control unit is configured to control ON/OFF of the first and second switching elements based on the outputs of the rechargeable battery temperature detector and the internal circuit voltage detector. a rechargeable battery temperature detector configured to produce an output indicating a temperature of the rechargeable battery;_ wherein the control unit is configured to control ON/OFF of the first and second switching elements based on the outputs of the rechargeable battery temperature detector and the internal circuit voltage detector.