Disclosed is a theft sensing system for sensing a theft of a fusion splicer device, using an information terminal. The theft sensing system comprises: a wireless communication unit for the fusion splicer device to communicate wirelessly with the information terminal; an authentication processing unit for performing an authentication process such that the fusion splicer device and information terminal can wirelessly connect; an acquisition unit for acquiring wireless state data between the fusion splicer device and information terminal mutually wirelessly connected by the authentication process; an assessment unit for assessing, on the basis of a change in the wireless state data acquired by the acquisition unit, whether the fusion splicer device has moved away from the information terminal; and a notification unit for performing a prescribed notification process on the information terminal if the assessment unit assesses that the fusion splicer device has moved away from the information terminal.