A power conversion device, which includes an insulation type full bridge converter and can switch a power transmission direction at a high speed, is provided. A DC/DC converter (10) constitutes a power conversion device, which operates as a first type converter that converts a voltage within a first range applied to a first input/output terminal pair into a voltage within a second range and outputs the voltage from a second input/output terminal pair or a second type converter that converts a voltage within the second range applied to the second input/output terminal pair into a voltage within the first range and outputs the voltage from the first input/output terminal pair, as a device that performs a specific state transition of the DC/DC converter (10) after a change rate of a magnitude of a current flowing through a winding of a primary or secondary side of a transformer (TR) with respect to time reaches a value within a predetermined change rate range.