An abnormality determination device for an additive manufacturing apparatus for building a part having three-dimensional shape by repeatedly forming a membrane of raw material and forming a cured layer having two-dimensional shape, the membrane formed by a blade in a build area, the raw material including ceramic particles and photocurable resin, the cured layer formed by irradiating the membrane with light in the build area, the abnormality determination device includes a controller configured to perform abnormality determination based on an image captured by an image sensor, the controller is configured to acquire the image of the membrane captured by the image sensor, detect a linear abnormal portion appearing in the membrane as a line extending along a movement direction of the blade based on the acquired image of the membrane, and determine that layering fault has occurred in response to detection of the linear abnormal portion.