A wearable device including a skin sensor and a processor is provided. The processor is configured to receive an authentication data for authenticating a user when a wearing state of the wearable device is adjacent to a skin surface of the user, share an authenticated state in response to a request from an electronic device when the authentication data matches a pre-stored data and the skin sensor determines that the wearable device does not leave the skin surface after the authentication data is received, and stop sharing the authenticated state when the skin sensor determines that the wearable device leaves the skin surface during the sharing.