Various embodiments of the present disclosure relate to an electronic device for using an amplifier to detect whether a user body is close to the electronic device and an operation method thereof. An electronic device according to an embodiment of the present disclosure may include: an antenna configured to be at least a part of an exterior of the electronic device; a variable element that has a capacitance in a designated range; and an amplifier connected to the variable element and configured to amplify a voltage of the variable element by a designated ratio and output an amplified voltage, wherein the capacitance of the variable element and the designated ratio may be configured so that a difference between a voltage of the antenna and the amplified voltage of the amplifier is smaller than a designated threshold value.