An electrical plug device includes a housing that is formed with two receptacles, a positioning member that is disposed in the housing and that includes a base, a fixed arm unit and a flexible arm unit, and a plug member that includes a pivot rod and two plug prongs receivable in the receptacles. The base, the fixed arm unit and the flexible arm unit cooperatively define an engaging groove. The pivot rod includes a rod body pivotally received in the engaging groove and a protrusion protruding from the rod body. The plug prongs are respectively secured in position when respectively protruding out of the receptacles via detachable engagement of the protrusion with and detachable abutment of the rod body against the flexible arm unit.