A cyclic silane having high purity, a composition containing a polysilane obtained by polymerization of the cyclic silane, and a silicon thin film are disclosed. A method for producing a cyclic silane of the formula (SiH2)n, where n is an integer of 4 to 6, includes reacting a cyclic silane compound of the formula (SiR1R2)n (where R1 and R2 are each a hydrogen atom, a C1-6 alkyl group, or a substituted or unsubstituted phenyl group) with a hydrogen halide in the presence of an aluminum halide to obtain a cyclic silane of the formula (SiR3R4)n (where R3 and R4 are each a halogen atom), and then distilling the solution, and reducing the cyclic silane of the formula (SiR3R4)n with hydrogen or lithium aluminum hydride. The distillation may be carried out at a temperature of 40° C. to 80° C. under a reduced pressure of 0 to 30 Torr.