A controller for a vehicle includes failure diagnosis circuitry and drive control circuitry. The failure diagnosis circuitry is configured to perform a failure diagnosis of an internal combustion engine system while an internal combustion engine is in operation. The drive control circuitry is configured to operate the internal combustion engine in a charge depleting mode operation in which an electric motor mainly moves the vehicle while the internal combustion engine is not run only for charging a battery. The drive control circuitry is configured to run the internal combustion engine if a predetermined condition is satisfied in the charge depleting mode operation. The drive control circuitry is configured to continue running the internal combustion engine in order to perform the failure diagnosis even if the predetermined condition is unsatisfied while the internal combustion engine is run in the charge depleting mode operation.