Disclosed is a polysilane having a repeating unit represented by general formula (1) given below. Also disclosed is a polysilane composition, comprising a polysilane having a repeating unit represented by general formula (2) given below and a cross linking agent: ##STR1## where, each of R.sup.1 and R.sup.3 is hydrogen, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms or a substituted or unsubstituted aryl group having 6 to 24 carbon atoms; R.sup.2 is a divalent hydrocarbon group having to 24 carbon atoms which can be substituted; R.sup.4 is a covalent bond, or a substituted or unsubstituted alkylene group having 1 to carbon atoms, or a substituted or unsubstituted arylene group having 6 to 24 carbon atoms; each of R.sup.5 to R.sup.9 is hydrogen, a substituted or unsubstituted alkyl group having 1 to 24 carbon atoms, a substituted or unsubstituted aryl group having 6 to 24 carbon atoms, or hydroxyl group, at least one of R.sup.5 to R.sup.9 being hydroxyl group; and X is a monovalent organic group having a reactive group capable of crosslinking upon exposure to light or by heating. If any of the polysilane and the polysilane composition of the present invention is exposed to light or heated, the polysilane molecules are crosslinked so as to provide a two or three dimensional polymer.