A power conversion system includes n (n being an integer of 2 or more) power conversion devices (P1 to P4) connected in parallel to a load (4); and a communication line (2) connected to the n power conversion devices (P1 to P4). Each of power conversion devices includes a communication circuit (10) which transmits a load current value detected by a current sensor (37) to each of other (n−1) power conversion devices through the communication line (2), and receives (n−1) load current values transmitted through the communication line (2) from other (n−1) power conversion devices; and an operation circuit (11) calculating a shared current and a cross current of the corresponding power conversion device based on the n load current values. Accordingly, a wiring line is prevented from becoming complicated even when the number of power conversion devices is increased.