A travel controller performs driving control of a vehicle at an autonomous driving level that is a first autonomous driving level in which a driver of the vehicle is not obligated to watch or a second autonomous driving level in which the driver is obligated to watch; notifies, for a predetermined period, the driver of a request for driving the vehicle or taking a driving posture allowing for the driving, when the autonomous driving level of the driving control changes from the first autonomous driving level to the second autonomous driving level; and determines an attention level of the driver, based on an output of a sensor provided for the vehicle. The attention level is a level of attention to driving. The travel controller further modifies the predetermined period so as to be shorter when the determined attention level is high than when the attention level is low.