A process for producing a cyclic silane compound, in which a chained polysilane is subjected to pyrolysis in the presence of an oxide of a transition metal belonging to Group 8 or Group 11 of the periodic table; and a process for producing a cyclic carbosilane compound, that includes subjecting a chained polysilane to pyrolysis in the presence of a simple substance of a metal selected from the group consisting of transition metal elements and elements belonging to Groups 12 to 15 of the periodic table, or a compound thereof.