An axle load measuring apparatus includes a displacement calculator, a storage, and an axle load calculator. The displacement calculator detects displacements of positions on a road caused by an axle load using a captured image of the road and a vehicle thereon. When a certain amount of load is applied to a predetermined position of the road, the storage stores a displacement function representing shape information of a spatial distribution of a displacement of the road originated from the predetermined position. The axle load calculator calculates the axle load based on the displacements of the positions and the displacement function.