An entry detection apparatus includes a position detection unit that detects presence of an entry prohibited road ahead of a vehicle based on a position of the vehicle and map data including information showing, for each road section, whether the road section is an entry prohibited road section, a sign detection unit that detects whether or not a pair of no-entry signs are present on both sides of a running course of the vehicle based on an image captured by an image sensor mounted on the vehicle, and determines whether or not the vehicle has passed between the no-entry signs, and an entry determination unit that determines that the vehicle has entered the entry prohibited road if the position detection unit detects presence of the entry prohibited road, and the sign detection unit determines that the vehicle has passed between the no-entry signs.