An electronic device has a casing with an article housing formed therein openable/closable by means of a lid. A locking mechanism locking the lid to a closing position comprises a locking member movably supported with respect to the casing and an engagement reception piece formed on the lid and engaging with the locking member. The locking member moves among a locking position where the locking member engages with the engagement reception piece to lock the lid to the closing position, a first unlocking position where the locking member retreats from the locking position and is removed from the engagement reception piece while the part of the locking member projects to the opening of the article housing, and a second unlocking position where the locking member retreats from the first unlocking position and the part of the locking member does not project to the opening of the article housing.