To provide a film forming method and film forming device which can efficiently form a film of film forming raw material on a material to be treated under a plasma atmosphere for reducing plasma damage on the material to be treated, and to especially provide a film forming method and film forming device of a gas barrier film.

In the film forming method, ionized film forming raw material is deposited on the material to be treated 1 under the plasma atmosphere. A magnetic field environment, in which a magnetic field line 2 faces a direction 9 separating from a film forming surface 3 of the material to be treated 1, is formed, and the film forming raw material is deposited on the film forming surface 3 of the material to be treated 1 in the magnetic field environment. A direction of the magnetic field line 2 is a direction of a magnetic field line directing from an N pole to an S pole of a magnet, and a direction of bouncing a charged particle 4 for forming plasma in the direction 9 separating from the film forming surface 3. Such the magnetic field line 2 can be achieved by arranging the N pole of a permanent magnet or electromagnet on a side closer to the side of supplying the film forming raw material, and arranging the S pole to a side apart from there or the like.