In an anomaly detection apparatus mounted in a vehicle, a model storage stores a driving model which is set corresponding to a travel location of the vehicle traveling on a roadway and represents a normal driving state as the vehicle is traveling at the travel location. A data acquirer acquires driving performance data representing the driving state of the vehicle. A degree-of-anomaly calculator calculates a degree of anomaly in the driving state based on the driving model stored in the model storage and the driving performance data acquired by the data acquirer. A vehicle-mounted transmitter, if the degree of anomaly calculated by the degree-of-anomaly calculator exceeds an anomaly determination value for determining the presence of an anomaly in the driving state, transmits at least the degree of anomaly and the travel location corresponding to the degree of anomaly to a monitoring center located external to the vehicle and detects an anomaly in the road condition based on the degree of anomaly.