An electronic device includes a circuit electrically connected to first and second contacts and a processor electrically connected to the circuit, wherein the circuit compares a first signal occurring by an electrical contact of the first contact and the external material with a first threshold value to generate a first comparison signal, compares a second signal occurring by an electrical contact of the second contact and the external material with a second threshold value to generate a second comparison signal, and generates a third signal based on a portion of the first and second comparison signals and provides the third signal to the processor, wherein the external material includes one of moisture and a foreign substance or the external connector, and the processor prevents recognizing a contact of the moisture or the foreign substance as a contact of the external connector based on a portion of the third signal.