To effectively suppress radiation and mixture of noise superimposed on a power line into a connection detection line. A power conversion device includes a connector having a wiring line which transmits DC power; and a housing in which the connector is arranged. The connector has a connection detection wiring line which detects whether the connector is connected with an external circuit. An opening part which connects with the connector is formed in the housing. An annular core formed of a magnetic substance is inserted through the opening part. The annular core is an annular member formed with a through-hole. The wiring line and the connection detection wiring line are introduced into an inside of the housing through the through-hole of the annular core.