Abstract: An objective of the present invention is to provide a process for producing a siliceous film which has a uniform quality independently of sites and in both the inside and outside of the grooves and is free from voids and cracks in the inside of the grooves. A substrate with the siliceous film can be produced by forming an insulating film having a high hydrogen content on a surface of a silicon substrate having concavoconvexes, then coating a composition containing a polysilazane compound on the substrate, and heating the coated substrate to convert the polysilazane compound to a silicon dioxide film.