A voltage drop protection apparatus is provided. The voltage drop protection apparatus includes a power source, a controller electrically connected with the power source and configured to control electronic device by using a power supplied from the power source, a transmission capacitor electrically connected with the power source and configured to accumulate a transmission power to be used when transmitting either one of an electromagnetic wave and a sound wave, and a voltage detector configured to detect a value of voltage applied from the power source toward the electronic device. When the voltage value detected by the voltage detector is lower than a predetermined threshold, the transmission capacitor applies the voltage at least to the controller.