In a method for manufacturing a three-dimensional shaped object in which layers formed by ejecting and curing ink including a curing resin are laminated, the method includes a layer forming process of forming the layers by using a composition for three-dimensional shaped object including powder for three-dimensional shaped object, and an ink ejecting process of ejecting an object formation ink and a sacrificial layer formation ink to the layers. In the ink ejecting process, the object formation ink and the sacrificial layer formation ink penetrate into the layers while forming a boundary between a region where the object formation ink penetrates in the layers and a region where the sacrificial layer formation ink penetrates into the layers.