Provided is a first mobile device having a card shape, the first mobile device including a storage unit configured to store one or more pieces of card payment information; a payment information transmission unit configured to transmit at least one of the one or more pieces of card payment information in a contact or contactless manner to a payment terminal; and a controller configured to determine whether the first mobile device is in a detached state with respect to a second mobile device or a cover of the second mobile device, and to determine whether to transmit the at least one of the one or more pieces of card payment information, based on the determination of whether the first mobile device is in the detached state.