To provide a movable partition device which can not only change the connection of the space in the interior simply, but form the interior as a continuous space giving satisfactory open feeling when opening.

This movable partition device is formed by fittings 10, 10 with a height from the floor surface 4 of the interior to the ceiling surface 5, and rails 12, 13 buried in the floor surface 4 and the ceiling surface 5 to slidably support the fittings, and by sliding of the fittings 10, 10, the opening part 1 between the respective rooms in the interior can be switched to the fully opening state, a partially opening state or the totally closed state.