A power conversion device is provided, which includes: a power conversion circuit that performs power conversion between a primary power and a secondary power; a buffer data accumulation circuit that, in a predetermined buffer cycle, repeatedly acquires data sets relating to a state of the power conversion circuit and store the data sets in a ring buffer; a state monitoring circuit that generates a trigger signal in a case where a state of a predetermined monitoring target satisfies a predetermined condition; and a data replication circuit that, in a case where a trigger signal is generated, stores, in a data storage circuit, a plurality of the data sets accumulated in the ring buffer in a target storage period including a time before a generation time of the trigger signal.