There is disclosed a power conversion apparatus 3 for converting polyphase ac power directly to ac power. A conversion circuit includes a plurality of first switching devices 311, 313, 315 and a plurality of second switching devices 312, 314, 316 connected, respectively, with the phases R, S, T of the polyphase ac power, and configured to enable electrical switching operation in both directions. Output lines 331, 332 formed by a pair of busbars are connected with the conversion circuit. The first switching devices and the second switching devices are so arranged that output terminals are arranged in a row. The output lines 331, 332 are connected with the output terminals and drawn out rectilinearly in one direction.