An electric power converter is equipped with a master converter and a slave converter that are connected in parallel with each other, and to a load. The master converter operates having priority over the slave converter. The slave converter includes a voltage sensor for detecting an output voltage of the electric power converter and a control unit for controlling an output of the slave converter based on a target command value. The control unit selects a current command value Ic2 received from the master converter as a target command value when a variation ΔV per predetermined time of a detected output voltage Vo2 is lower than a variation ΔVth1. The control unit selects a voltage command value Vc2a calculated so as to suppress the output voltage Vo2 from changing as the target command value when the variation ΔV exceeds the variation ΔVth1.