A starter controller incorporated in a starter control system for controlling actuation of a first starter and a second starter to start an engine. The second starter is an alternating-current (AC) starter. The starter control system actuates the first starter in response to an engine start-up request, deactivates the first starter before completion of engine start-up, and activates the second starter while the second starter is being rotated by rotation of an engine rotary shaft. In the starter controller, a determination unit is configured to, under a condition where the engine rotary shaft is rotating after deactivation of the first starter, determine whether or not recognition of rotation of the second starter is complete. A fail-safe unit is configured to, if the recognition of rotation of the second starter is complete, perform predefined fail-safe processing responding to an abnormality in the second starter.