In one embodiment, the invention can be an electric toothbrush. The electric toothbrush may include a driving module configured to oscillate a brush unit; an acceleration sensor configured to generate an output signal; a signal extraction module configured to extract from the output signal (a) a first signal having a frequency at a first threshold or higher and (b) a second signal having a frequency at a second threshold or lower; a brushing site estimation module configured to estimate a brushing site of the brush unit based on the output signal of the acceleration sensor; and a correction module configured to correct the brushing site estimated by the brushing site estimation module based on an amplitude of the first signal and an amplitude of the second signal.