A power conversion device (100, 100a) comprising: - a power converter configured to perform power conversion between three-phase AC and DC, the power converter including a plurality of leg circuits each having a positive arm and a negative arm which are connected in series and are connected to an AC line for each phase, the plurality of leg circuits being connected in parallel between positive and negative DC buses (2, 3); and - a control device configured to control the power converter, wherein each of the positive arm and the negative arm of each leg circuit includes a converter cell comprising a series unit (32, 42) including a plurality of semiconductor switching elements (30, 40) connected in series to each other; and a DC capacitor (34, 44) connected in parallel to the series unit (32, 42), wherein the control device includes a voltage command generation unit configured to generate a positive arm voltage command (Vp+) for the positive arm and a negative arm voltage command (Vp-) for the negative arm, and is adapted to perform output control of each converter cell in the positive arm and the negative arm by PWM control, and further includes a PWM circuit, wherein the voltage command generation unit includes: - an AC current control unit configured to adjust an AC control command for controlling an AC current component flowing through the AC line for each phase; - an arm balance control unit configured to, on the basis of positive capacitor voltage which indicates at least one of a voltage of the DC capacitors (34, 44) in the positive arm and negative capacitor voltage which indicates at least one of a voltage of the DC capacitor (34, 44) in the negative arm, calculate a first voltage adjustment value (ΔVc) for balancing the positive capacitor voltage and the negative capacitor voltage; - an AC-side command calculation unit configured to output an AC voltage command for AC voltage to be output to the AC line for each phase; and - a command distributing unit configured to determine the positive arm voltage command (Vp+) and the negative arm voltage command (Vp-) on the basis of the AC voltage command and a DC voltage command for DC voltage between the DC buses (2, 3), and wherein the AC-side command calculation unit is adapted to adjust the AC control command using the first voltage adjustment value (ΔVc), and calculate the AC voltage command on the basis of the adjusted AC command, so that the positive arm and the negative arm respectively has an opposite polarity of the charging/discharging of the DC capacitor (34, 44), thereby the charging /discharging of the DC capacitor (34, 44) in the positive arm and the DC capacitor (34, 44) in the negative arm are opposite to each other. - a power converter configured to perform power conversion between three-phase AC and DC, the power converter including a plurality of leg circuits each having a positive arm and a negative arm which are connected in series and are connected to an AC line for each phase, the plurality of leg circuits being connected in parallel between positive and negative DC buses (2, 3); and - a control device configured to control the power converter, - an AC current control unit configured to adjust an AC control command for controlling an AC current component flowing through the AC line for each phase; - an arm balance control unit configured to, on the basis of positive capacitor voltage which indicates at least one of a voltage of the DC capacitors (34, 44) in the positive arm and negative capacitor voltage which indicates at least one of a voltage of the DC capacitor (34, 44) in the negative arm, calculate a first voltage adjustment value (ΔVc) for balancing the positive capacitor voltage and the negative capacitor voltage; - an AC-side command calculation unit configured to output an AC voltage command for AC voltage to be output to the AC line for each phase; and - a command distributing unit configured to determine the positive arm voltage command (Vp+) and the negative arm voltage command (Vp-) on the basis of the