A housing of a power conversion device is partitioned into sealed and open parts. A first housing containing a primary-side electronic component connected to a primary winding of a transformer has a first opening through which a first connection conductor is inserted, the first opening being blocked by an aperture surface included in a third housing containing the transformer and filled with an insulating member. A shortest distance between the first connection conductor and an edge of the first opening is greater than or equal to a first threshold. A second housing containing a secondary-side electronic component connected to a secondary winding of the transformer has a second opening through which a second connection conductor is inserted, and is blocked by the aperture surface. A shortest distance between the second connection conductor and an edge of the second opening is greater than or equal to a second threshold.