There is provided a polygermane compound forming a film having a high refractive index and thermal stability, and containing a sulfur atom-containing organic group as a group bonded to a germanium atom. A polygermane compound comprising a sulfur atom-containing organic group as a group bonded to a germanium atom, in which the sulfur atom-containing organic group is a group of Formula [1]: -L-Z  [1] where L is a single bond, a C1-6 alkylene group, or a C4-20 arylene group optionally substituted with a C1-6 alkyl group; and Z is a C1-20 sulfide group, a C1-14 cyclic sulfide group optionally substituted with a C1-6 alkyl group, a C2-20 alkyl group containing a sulfide bond, or a C5-20 aralkyl group containing a sulfide bond, with a proviso that when L is a single bond, Z is not a C1-20 sulfide group.