A three-level power converter comprising a power-conversion circuit unit for one phase that is arranged to select any of potentials of a higher-side DC terminal, an intermediate-potential terminal, and a lower-side DC terminal, and to output the selected potential to an AC terminal, where the power-conversion circuit unit includes a first dual-element power module that includes an outer switching element on the higher potential side of the three-level power converter and a clamp element on the higher potential side of the three-level power converter, a second dual-element power module that includes an inner switching element on the higher potential side of the three-level power converter and an inner switching element on the lower potential side of the three-level power converter, and a third dual-element power module that includes an outer switching element on the lower potential side of the three-level power converter and a clamp element on the lower potential side of the three-level power converter, wherein the first to third dual-element power modules (1a, 1b, 1c) are dual-element triple-terminal power modules with the same configuration, each of which includes a first electrode (M11, M21, M31) that is connected to a higher-side potential portion of one of the switching elements (10a, 10b, 10c), a second electrode (M12, M22, M32) that is connected to a connection portion between a lower-side potential portion of the one of the switching elements (10a, 10b, 10c) and a higher-side potential portion of the other switching element (12a, 12b, 12c), and a third electrode (M13, M23, M33) that is connected to a lower-side potential portion of the other element (12a, 12b, 12c), and the first electrode in the first dual-element power module is connected to the higher-side DC terminal, the second electrode in the first dual-element power module and the first electrode in the second dual-element power module are connected to each other, the third electrode in the first dual-element power module is connected to the intermediate-potential terminal, the first electrode in the third dual-element power module is connected to the intermediate-potential terminal, the second electrode in the second dual-element power module is connected to the AC terminal, the third electrode in the second dual-element power module and the second electrode in the third dual-element power module are connected to each other, and the third electrode in the third dual-element power module is connected to the lower-side DC terminal; wherein the first to third electrodes (M11, M12, M13, M21, M22, M23, M31, M32, M33) in the first to third dual-element power modules (1a, 1b, 1c) are provided on an electrode mounting surface at one of main-surface sides of a module casing, and the first electrode (M11, M21, M31) and the third electrode (M13, M23, M33) are arrayed in a direction orthogonal to a longitudinal direction of the module casing on one of the end sides in the longitudinal direction, and the second electrode (M12, M22, M32) is arranged on the other end side in the longitudinal direction of the module casing, wherein the first and third dual-element power modules (1a, 1c) are arranged on a plane such that longitudinal side-surfaces of their respective module casings are adjacent to each other, and electrode mounting surfaces of the module casings are directed in the same direction, and the second dual-element power module is arranged such that a center line of a module casing in a longitudinal direction extends parallel to a center plane, the center plane being orthogonal to said plane and crossing said plane between the centers of the first dual-element power module and the third dual-element power module, and wherein the second dual-element power module is arranged such that the second electrode is positioned on the crossing of said plane with the center plane, and wherein the second dual-element power module, the first electrode and the third electrode are arranged symmetrically with respect to the center plane.