A power conversion device comprising a capacitor, a positive-electrode bus bar, a negative-electrode bus bar, bus bars (61, 62, 63, 64) that are each configured to be connected to an AC-phase terminal of for instance a motor wire, a specific purpose bus bar (61, 62, 63, 64), and semiconductor modules (110; 111, 112, 113, 114), each semiconductor module having a half-bridge configuration in which two semiconductor elements are arranged in series, wherein the capacitor and each semiconductor module have a cuboidal shape, and wherein positive-electrode terminal modules, negative-electrode terminal modules, and terminal modules for inputting or outputting AC or for a specific purpose are mounted on one side of each semiconductor module, wherein each terminal module (6a, 6b, 6c) has a cuboidal shape, the semiconductor modules are mounted side-by-side on a cooling equipment such that for each semiconductor module the module side opposite to its side on which the terminal modules (6a, 6b, 6c) are mounted is in contact with the cooling equipment, and such that the positive-electrode terminal modules are lined up along first lines, the negative-electrode terminal modules are lined up along second lines, and the terminal modules for inputting or outputting AC or for a specific purpose are lined up along third lines, wherein the first lines, the second lines, and the third lines are parallel lines, wherein the positive-electrode bus bar is connected to each positive-electrode terminal of each semiconductor module, the negative-electrode bus bar is connected to each negative-electrode terminal of each semiconductor module, and wherein the bus bars (61, 62, 63, 64) that are each configured to be connected to an AC_phase terminal, and the specific purpose bus bar (61, 62, 63, 64) extend in the same direction along each terminal module for inputting or outputting AC or for a specific purpose, and wherein the positive-electrode bus bar has an L-shape and overlays the positive-electrode terminal modules, the negative electrode bus bar has an L-shape and overlays the negative-electrode terminal modules, and the capacitor is disposed on the concave side of an L-shaped bus bar (40; 50). wherein the capacitor and each semiconductor module have a cuboidal shape, and wherein positive-electrode terminal modules, negative-electrode terminal modules, and terminal modules for inputting or outputting AC or for a specific purpose are mounted on one side of each semiconductor module, wherein each terminal module (6a, 6b, 6c) has a cuboidal shape, the semiconductor modules are mounted side-by-side on a cooling equipment such that for each semiconductor module the module side opposite to its side on which the terminal modules (6a, 6b, 6c) are mounted is in contact with the cooling equipment, and such that the positive-electrode terminal modules are lined up along first lines, the negative-electrode terminal modules are lined up along second lines, and the terminal modules for inputting or outputting AC or for a specific purpose are lined up along third lines, wherein the first lines, the second lines, and the third lines are parallel lines, wherein the positive-electrode bus bar is connected to each positive-electrode terminal of each semiconductor module, the negative-electrode bus bar is connected to each negative-electrode terminal of each semiconductor module, and wherein the bus bars (61, 62, 63, 64) that are each configured to be connected to an AC_phase terminal, and the specific purpose bus bar (61, 62, 63, 64) extend in the same direction along each terminal module for inputting or outputting AC or for a specific purpose, and wherein the positive-electrode bus bar has an L-shape and overlays the positive-electrode terminal modules, the negative electrode bus bar has an L-shape and overlays the negative-electrode terminal modules, and the capacitor is disposed on the concave side of an L-shaped bus bar (40; 50).