An electric heating device includes a box-shaped plug socket provided with a socket-side electroconductive part electrically connected to an electric heater; a power source plug provided with a plug-side electroconductive part electrically connectable to the socket-side electroconductive part and attachable to and detachable from the plug socket; a movement-restricting mechanism for restricting the movement of a protective member both toward and away from a socket-side electroconductive part in a protected state in which the protective member closes an opening of the plug socket and the socket-side electroconductive part are positioned within an interior space; and a switching mechanism for switching the protective member from a restricted movement state into a restriction released state, in which the restriction of movement by the movement restriction mechanism is released, as the power source plug is inserted into the plug socket.