VEHICLE-MOUNTED CONTROL APPARATUS

A vehicle-mounted control apparatus includes a first storage unit that stores a rule at a time when communication data is normal, a second storage unit that stores part of rules stored in the first storage unit, a monitoring unit that monitors whether or not communication data is normal, a reference-rule recording unit that records a rule that coincides with under-monitoring communication data and the number of coincidences therebetween, and a rule-updation unit that updates a rule stored in the second storage unit, based on a rule stored in the first storage unit and a record in the reference-rule recording unit.