To provide a controller which enables the drive of a motor without increasing an output current without generating low-frequency torque pulsation or noise, even in case that it outputs voltage 0.866 times as high as the power voltage.

An AC-AC direct converter includes first absolute value limiting means 11u, 11v, 11w which limit first phase voltage command of each phase so that the instant absolute value may be a first reference value or under, a means 12 which calculates zero-phase components from these output, addition means 13u, 13v, 13w which calculate second phase voltage commands by adding the above zero phase components to the first phase voltage command, and a second absolute value limiting means 2 which calculates a third phase voltage command by limiting the second phase voltage command so that the instant absolute value may be a second reference value or under. It calculates the on-off command to the semiconductor switching element of the AC-AC direct converter, using a third phase voltage command.