A vehicular authentication device that includes: a first processor; and a second processor. The first processor is configured to: perform a first permission to permit release of a steering lock of a vehicle in a case in which a verification of key information of the vehicle has been performed successfully, and in a case in which the steering lock has been released by the first permission, perform a second permission to permit deactivation of an immobilizer of the vehicle based on a successful verification of biometric information by the second processor.