PURPOSE: To form a uniform thin film of high quality even on a large-sized substrate by providing a plurality of crucibles and moving the substrate while irradiating the substrate of the whole width with a beam.

CONSTITUTION: A distance between a sealed crucible 2 and a substrate is so set that the beam angle of cluster ions is set in a range that a thin film formed on a substrate 10 becomes homogeneous, and the crucibles 2 are so disposed that ion beams of a plurality (4 in the drawing) of crucibles 2 form a film in a uniform thickness on the substrate face even in a direction perpendicular to the moving direction of the substrate 10. The crucibles 2 simultaneously generate depositing substances, and generates cluster ions to irradiate the ions on the substrate 10. Here, a substrate holder is conveyed slowly in a direction perpendicular to the arranging direction of the crucibles 2 at a constant speed. Thus, a deposited film is uniformly formed on the whole substrate 10, thereby increasing the area of the substrate 10.