An additive manufacturing system for manufacturing an additively-manufactured object by welding a filler metal and depositing weld beads, the additive manufacturing system comprising: an additive manufacturing device, the system being characterised by the following: a creation means configured to create shape data of a weld bead as first shape data based on design data of the additively-manufactured object; a determination means configured to determine a welding condition for forming the first shape data; an acquisition means configured to acquire, as second shape data, shape data of a weld bead formed using the welding condition determined by the determination means; a derivation means configured to derive a difference between a welding condition corresponding to the first shape data and a welding condition corresponding to the second shape data by inputting the first shape data and the second shape data or a difference between the first shape data and the second shape data to a learned model, the learned model being generated by performing a learning process using two pieces of shape data of a weld bead or a difference between the two pieces of shape data as input data and a difference between welding conditions corresponding to the difference between the two pieces of shape data as output data; and an adjustment means configured to adjust the welding condition determined by the determination means using the difference derived by the derivation means. an additive manufacturing device, the system being characterised by the following: a creation means configured to create shape data of a weld bead as first shape data based on design data of the additively-manufactured object; a determination means configured to determine a welding condition for forming the first shape data; an acquisition means configured to acquire, as second shape data, shape data of a weld bead formed using the welding condition determined by the determination means; a derivation means configured to derive a difference between a welding condition corresponding to the first shape data and a welding condition corresponding to the second shape data by inputting the first shape data and the second shape data or a difference between the first shape data and the second shape data to a learned model, the learned model being generated by performing a learning process using two pieces of shape data of a weld bead or a difference between the two pieces of shape data as input data and a difference between welding conditions corresponding to the difference between the two pieces of shape data as output data; and an adjustment means configured to adjust the welding condition determined by the determination means using the difference derived by the derivation means. a creation means configured to create shape data of a weld bead as first shape data based on design data of the additively-manufactured object; a determination means configured to determine a welding condition for forming the first shape data; an acquisition means configured to acquire, as second shape data, shape data of a weld bead formed using the welding condition determined by the determination means; a derivation means configured to derive a difference between a welding condition corresponding to the first shape data and a welding condition corresponding to the second shape data by inputting the first shape data and the second shape data or a difference between the first shape data and the second shape data to a learned model, the learned model being generated by performing a learning process using two pieces of shape data of a weld bead or a difference between the two pieces of shape data as input data and a difference between welding conditions corresponding to the difference between the two pieces of shape data as output data; and an adjustment means configured to adjust the welding condition determined by the determination means using the difference derived by the derivation means.