To provide a material including: a silicon-containing polymer having at least an alkali-soluble group and is represented by the following general formula (1); and an organic solvent capable of dissolving the silicon-containing polymer. (SiO.sub.4/2).sub.a(R.sup.1.sub.tSiO.sub.(4-t)/2).sub.b(O.sub.1/2R.sup.2).- sub.c general formula (1) where R.sup.1 represents at least one of a monovalent organic group, hydrogen atom and hydroxyl group, R.sup.2 represents at least one of a monovalent organic group and hydrogen atom (where R.sup.1 and R.sup.2 each may appear twice or more, and at least one of R.sup.1 and R.sup.2 contains an alkali-soluble group), "t" represents an integer of 1 to 3, "a," "b," and "c" represent the relative proportions of their units (where a.gtoreq.0, b.gtoreq.0 and c.gtoreq.0, and "a," "b," and "c" are not 0 at the same time), and (R.sup.1.sub.tSiO.sub.(4-t)/2).sub.b may appear twice or more.