An electric working machine comprising: a motor ; an acceleration sensor configured to detect a vibration of the electric working machine and output a detection signal corresponding to the vibration; a load-determiner configured to determine whether the electric working machine is placed in no-load-imposed state or in load-imposed state based on the detection signal from the acceleration sensor , the load-determiner being configured to drive the motor in a low-speed rotation mode in response to a determination by the load-determiner that the electric working machine is placed in the no-load-imposed state, and the load-determiner being further configured to drive the motor in a high-speed rotation mode in response to a determination by the load-determiner that the electric working machine is placed in the load-imposed state; a filter part having a cutoff frequency, the filter part being configured to remove, based on the cutoff frequency, an unwanted signal component from the detection signal outputted from the acceleration sensor , the filter part being further configured to input, to the load-determiner , the detection signal with the unwanted signal component removed, and the unwanted signal component corresponding to a vibration of the electric working machine unnecessary for a determination by the load-determiner ; and a filter-property setting part configured to change the cutoff frequency of the filter part such that the cutoff frequency in the high-speed rotation mode is higher than the cutoff frequency in the low-speed rotation mode, wherein the filter-property setting part is configured to change the cutoff frequency of the filter part in response to an elapse of a given length of time since a rotation mode of the motor is changed by the load-determiner . a motor ; an acceleration sensor configured to detect a vibration of the electric working machine and output a detection signal corresponding to the vibration; a load-determiner configured to determine whether the electric working machine is placed in no-load-imposed state or in load-imposed state based on the detection signal from the acceleration sensor , the load-determiner being configured to drive the motor in a low-speed rotation mode in response to a determination by the load-determiner that the electric working machine is placed in the no-load-imposed state, and the load-determiner being further configured to drive the motor in a high-speed rotation mode in response to a determination by the load-determiner that the electric working machine is placed in the load-imposed state; a filter part having a cutoff frequency, the filter part being configured to remove, based on the cutoff frequency, an unwanted signal component from the detection signal outputted from the acceleration sensor , the filter part being further configured to input, to the load-determiner , the detection signal with the unwanted signal component removed, and the unwanted signal component corresponding to a vibration of the electric working machine unnecessary for a determination by the load-determiner ; and a filter-property setting part configured to change the cutoff frequency of the filter part such that the cutoff frequency in the high-speed rotation mode is higher than the cutoff frequency in the low-speed rotation mode, wherein the filter-property setting part is configured to change the cutoff frequency of the filter part in response to an elapse of a given length of time since a rotation mode of the motor is changed by the load-determiner . <EOS>