As a geometric application of polarized log Hodge structures, we show the following. Let M sm H be a projective variety which is a compactification of the coarse moduli space of surfaces of general type constructed by Kawamata, Kollár, Shepherd-Barron, Alexeev, Mori, Karu, et al., and let Γ\D Σ be a log manifold which is the fine moduli space of polarized log Hodge structures constructed by Kato and Usui. If we take a suitable finite cover M → M i of any irreducible component M i of M sm H , and if we assume the existence of a suitable fan Σ, then there is an extended period map ψ : M → Γ\D Σ and its image is the analytic subspace associated to a separated compact algebraic space. The point is that, although Γ\D Σ is a "log manifold" with slits, the image ψ(M ) is not affected by these slits and is a classical familiar object: a separated compact algebraic space.