An additive manufacturing support device includes reading circuitry that reads shaped article data that is data indicating the three-dimensional shape of a shaped article, first generating circuitry that generates primary data that is data indicating the three-dimensional shape of a primary separated portion provided in a region where a cutting part of a cutting apparatus passes between the plate and the shaped article, and second generating circuitry that generates, based on a machining allowance between the cutting part and an object to be cut in a process in which the cutting part passes between the plate and the shaped article, secondary data for reducing change in the machining allowance.