A power-driven grass mower includes an operation division (3) having a grass cutter (9) a motor division (6) having an electric motor and a power-source division (8) having a battery (7), wherein the operation division (3) is provided with a first means for watching if the motor division is locked for some reason or other, and a second means for putting the motor division into the inching operation in response to any signal from the first means indicating that the motor division (6) is in a locking condition.
