PURPOSE: To provide a liquid thin film like a thin transparent film improved in sense of human interest and transparency by making thickness of the liquid film thin, in a liquid thin film forming device used for the device for forming a spherical or a hanging-bell shaped liquid film and arranging ornaments, etc., in the liquid film.

CONSTITUTION: This device is used for jetting a liquid from a jetting port 11 in a thin film form, and in this thin liquid film forming device 1, a crosssectional area of the flow path 12 toward the jetting port 11 is made equal or gradually decreased toward the port 11.