An additive manufacturing apparatus includes a supporting portion, a powder supplying portion, a flattening member, a curing portion, and a controller. The supporting portion is configured to detachably support a shaping stage. The powder supplying portion is configured to supply powder. The flattening member is configured to move in a scanning manner above the shaping stage attached to the supporting portion. The controller is configured to execute a measuring process of detecting inclination between a shaping surface of the shaping stage attached to the supporting portion and a trajectory plane of a trajectory of scanning movement of the flattening member, an adjustment process of adjusting an orientation of the shaping stage on a basis of a detection result of the measuring process such that a degree of parallel between the shaping surface and the trajectory plane increases, a powder layer formation process, and a curing process.