Provided are a resin reservoir (1) for photocuring for use in a 3D printer and a 3D printer using the resin reservoir (1). The resin reservoir (1) comprises: a reservoir body (11) for accommodating a liquid photosensitive resin, at least one side wall of the reservoir body (11) being an optically-transmissive wall (111); a transverse guide element (12) disposed at the reservoir body (11); and a load-bearing element (13) disposed inside the reservoir body (11) and capable of moving transversely along the guide element (12), wherein a load-bearing surface of the load-bearing element (13) faces the optically-transmissive wall (111). The resin reservoir (1) and the 3D printer enable a printed object to be transversely formed at the load-bearing element (13) and kept immersed in the liquid photosensitive resin, and a buoyancy provided by the liquid photosensitive resin can substantially offset the weight of the printed object. Therefore, structural strengths of the load-bearing element (13) and a transmission unit do not need to be reinforced, and the size of an object to be printed can be increased from 14 inches to 20-120 inches.