A semiconductor integrated circuit includes: a main circuit; a non-volatile memory; and a self-diagnosis circuit configured to execute, when the semiconductor integrated circuit is to be powered off, self-diagnosis processing in which the main circuit is diagnosed and a diagnosis execution record indicating whether the diagnosis is completed and a diagnosis result indicating a result of the diagnosis are stored in the non-volatile memory. The self-diagnosis circuit is configured to: determine, when the semiconductor integrated circuit is powered on, whether there is a failure in the main circuit by reading the diagnosis execution record and the diagnosis result out of the non-volatile memory; and shift a state of the main circuit to a safe state when determining that there is a failure in the main circuit, and instruct the main circuit to start normal operation when determining that there is no failure in the main circuit.