Disclosed is a theft sensing system for sensing a theft of a fusion splicer by using an information terminal. The system includes a wireless communication unit that enables the fusion splicer to perform wireless communication with the information terminal, an authentication processing unit that performs an authentication process such that the fusion splicer and the information terminal are wirelessly connected to each other, an acquisition unit that acquires wireless situation data between the fusion splicer and the information terminal which are wirelessly connected to each other, a decision unit that decides whether the fusion splicer moves in a direction away from the information terminal based on a change in the wireless situation data acquired by the acquisition unit, and a notification unit that performs a predetermined notification process in the information terminal when the decision unit decides that the fusion splicer moves in the direction away from the information terminal.