A power conversion device comprising a capacitor , a positive-electrode bus bar , a negative-electrode bus bar , bus bars that are each configured to be connected to an AC-phase terminal of for instance a motor wire, a specific purpose bus bar , 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 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 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 that are each configured to be connected to an AC_phase terminal, and the specific purpose bus bar 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 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 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 that are each configured to be connected to an AC_phase terminal, and the specific purpose bus bar 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). <EOS>