A fitting adaptor is for fitting a cable connector to a device connector of an electrical device. The fitting adaptor includes a panel; an intermediate connector attached to the panel to be movable relative to the panel; a locking mechanism disposed on the panel; and an elastic member disposed on at least one of the intermediate connector and the locking mechanism, or between the panel and the intermediate connector. The intermediate connector includes a cable connector side connecting portion and a device connector side connecting portion, so that the elastic member urges the device connector side portion against the device connector.