A transformer including annular iron cores (32, 103) composed of laminas of amorphous iron and windings (9, 10, 11, 101), which transformer is used in an upright position in which the cores (32, 103) have upper portions and lower portions below the upper portions, the laminas in the upper portion extending horizontally when the transformer is in the upright position wherein: when the transformer is not in the upright position, the upper portions of the cores (32, 103) are supported by a first upper core supporting member, the first upper core supporting member being disposed along first end surfaces of the upper portions of the cores (32, 103) when the transformer is in the upright position, the first end surfaces being perpendicular to faces of the laminas, and a second upper core supporting member the second upper core supporting member being disposed along second end surfaces of the upper portions of the cores (32, 103) when the transformer is in the upright position, the second end surfaces being opposite and parallel to the first end surfaces of the cores (32, 103); the first upper core supporting member and the second upper core supporting member extend in the direction perpendicular to the faces of the laminas of amorphous iron, and the cores (32, 103) are interposed between the first upper core supporting member and the second upper core supporting member; the first upper core supporting member and the second upper core supporting member are provided with hooks (16-1, 16-2, 16-3, 16-4, 17-1, 17-2, 17-3, 17-4), the hooks (16-1, 16-2, 16-3, 16-4) of the first upper core supporting member extending toward the second upper core supporting member and the hooks (17-1, 17-2, 17-3, 17-4) of the second upper core supporting member extending toward the first upper core supporting member; bridging members (28, 29, 30, 31) are disposed on opposing pairs (16-1 and 17-1, 16-2 and 17-2, 16-3 and 17-3, 16-4 and 17-4) of the hooks (16-1, 16-2, 16-3, 16-4, 17-1, 17-2, 17-3, 17-4) of the first and second upper core supporting members (16, 17); and the cores (32, 103) are supported by the bridging members (28, 29, 30, 31) when the transformer is in the upright position. when the transformer is not in the upright position, the upper portions of the cores (32, 103) are supported by a first upper core supporting member, the first upper core supporting member being disposed along first end surfaces of the upper portions of the cores (32, 103) when the transformer is in the upright position, the first end surfaces being perpendicular to faces of the laminas, and a second upper core supporting member the second upper core supporting member being disposed along second end surfaces of the upper portions of the cores (32, 103) when the transformer is in the upright position, the second end surfaces being opposite and parallel to the first end surfaces of the cores (32, 103); the first upper core supporting member and the second upper core supporting member extend in the direction perpendicular to the faces of the laminas of amorphous iron, and the cores (32, 103) are interposed between the first upper core supporting member and the second upper core supporting member; the first upper core supporting member and the second upper core supporting member are provided with hooks (16-1, 16-2, 16-3, 16-4, 17-1, 17-2, 17-3, 17-4), the hooks (16-1, 16-2, 16-3, 16-4) of the first upper core supporting member extending toward the second upper core supporting member and the hooks (17-1, 17-2, 17-3, 17-4) of the second upper core supporting member extending toward the first upper core supporting member; bridging members (28, 29, 30, 31) are disposed on opposing pairs (16-1 and 17-1, 16-2 and 17-2, 16-3 and 17-3, 16-4 and 17-4) of the hooks (16-1, 16-2, 16-3, 16-4, 17-1, 17-2, 17-3, 17-4) of the first and second upper core supporting members (16, 17); and the cores (32, 103) are supported by the bridging members (28, 29, 30, 31) when the transformer is in the upright position.