There is disclosed a power conversion apparatus 3 for converting polyphase ac power directly to ac power. A conversion circuit includes first switching devices 311, 313, 315 and 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. There are provided input lines R, S, T connected with input terminals of the switching devices and output lines P, N connected with output terminals of the switching devices. The output terminals of the first switching devices and the output terminals of the second switching devices are, respectively, arranged in a row. The first switching devices and second switching devices are arranged side by side with respect to a direction of the rows. The output lines are disposed below the input lines in an up and down direction.