To provide an anti-theft control device capable of continuously operating a start electric motor by preventing cut-off of the start electric motor due to voltage drop of an on-vehicle battery.

The anti-theft control device comprises an electromagnetic relay including a starter switch 4a and an always opening contact 3a for supplying power from the on-vehicle battery 2 to the electric motor M for start, an anti-theft switch 8a inserted into the electromagnetic relay in series, a determining means 6a for generating a start allowance signal DR1 for closing the anti- theft switch 8a when a security code of an operation key 7a matches with an intrinsic code, a power supply switch 4b for supplying power from the on- vehicle battery 2 to the determining means 6a, and self holding circuits 8c and 8d for holding a closing state of the anti-theft switch. Respective switches 4a and 4b are closed by the operation key 7a, and the self holding circuits 8c and 8d are set in response to the start allowance signal DR1.