A grid connection power conversion device for connecting a distributed power supply to a three-phase commercial power system is provided. The power conversion device comprises an inverter, an instantaneous voltage detection circuitry to detect a maximum three-phase instantaneous voltage value of the commercial power system, a line voltage detection circuitry to detect a maximum value of each of three line voltages, an instantaneous voltage drop detection circuitry to detect an instantaneous voltage drop, and an output current control circuitry to control an output current value from the inverter. When the instantaneous voltage drop detection circuitry detects an instantaneous voltage drop, the output current control circuitry reduces the output current value from the inverter to an output current value corresponding to a minimum value among the four maximum voltage values which are the maximum three-phase instantaneous voltage value and the maximum values of the three line voltages.