The invention provides an antitheft apparatus for equipment with a prime mover, capable of using the antitheft function of the equipment with the prime mover and easily acquiring the operating history of the equipment. The antitheft apparatus for equipment with the prime mover comprises: a prime mover (electric motor 22); an equipment with the prime mover (small type electric motor 10); an equipment control unit (control ECU 32) for controlling the action of the equipment and storing the operating history of the equipment; and an authentication unit (authentication ECU 34) that acquires ID information from an electronic key when the key with the ID information is operated, determines whether the acquired ID information corresponds with authentication ID information, and permits the contro unit to start the prime mover when the acquired ID information is determined to correspond with authentication ID information, so as to prevent the device being stolen, wherein the authenticator acquires the history from the control unit and transmits the acquired history to the key when the key is operated.