A forming apparatus for forming a three-dimensional object by additive manufacturing, the apparatus comprising: an inkjet head configured to eject an ink droplet by inkjet scheme; a platform comprising a base member configured to support the three-dimensional object being formed, the platform being disposed at a position facing the inkjet head; a main scanning driver configured to cause the inkjet head to perform a main scanning operation in which the inkjet head moves relative to the platform in a predetermined main scanning direction while ejecting an ink droplet; a sub-scanning driver configured to cause the inkjet head to move relative to the platform in a sub-scanning direction orthogonal to the main scanning direction; a deposition direction driver configured to change the distance between the inkjet head and the platform by moving at least one of the platform and the inkjet head; and a roller configured to flatten a layer of ink formed by the inkjet head by moving relative to the platform together with the inkjet head during the main scanning operation, wherein, in between the main scanning operations, the sub-scanning driver is configured to cause the inkjet head to perform a sub-scanning operation in which the inkjet head moves relative to the platform by a predetermined forwarding distance in a sub-scanning moving direction, which is a predetermined direction in the sub-scanning direction, wherein, during the sub-scanning operation, the roller is configured to move relative to the platform in the sub-scanning moving direction together with the inkjet head, and wherein the roller comprises a first end on a forward end in the sub-scanning moving direction and a second end on a rearward end in the sub-scanning moving direction, and the roller is disposed in a tilted manner such that the height in the deposition direction of the second end on the rearward end is higher than the height in the deposition direction of the first end on the forward end. an inkjet head configured to eject an ink droplet by inkjet scheme; a platform comprising a base member configured to support the three-dimensional object being formed, the platform being disposed at a position facing the inkjet head; a main scanning driver configured to cause the inkjet head to perform a main scanning operation in which the inkjet head moves relative to the platform in a predetermined main scanning direction while ejecting an ink droplet; a sub-scanning driver configured to cause the inkjet head to move relative to the platform in a sub-scanning direction orthogonal to the main scanning direction; a deposition direction driver configured to change the distance between the inkjet head and the platform by moving at least one of the platform and the inkjet head; and a roller configured to flatten a layer of ink formed by the inkjet head by moving relative to the platform together with the inkjet head during the main scanning operation, wherein, in between the main scanning operations, the sub-scanning driver is configured to cause the inkjet head to perform a sub-scanning operation in which the inkjet head moves relative to the platform by a predetermined forwarding distance in a sub-scanning moving direction, which is a predetermined direction in the sub-scanning direction, wherein, during the sub-scanning operation, the roller is configured to move relative to the platform in the sub-scanning moving direction together with the inkjet head, and wherein the roller comprises a first end on a forward end in the sub-scanning moving direction and a second end on a rearward end in the sub-scanning moving direction, and the roller is disposed in a tilted manner such that the height in the deposition direction of the second end on the rearward end is higher than the height in the deposition direction of the first end on the forward end.