Optical probe methods for in vivo assessments of cutaneous photoaging are necessary in fields such as anti-aging dermatology and skin cosmetic development. We investigated the relation between wrinkle direction and collagen orientation in ultraviolet-B-exposed (UVB-exposed) skin using polarization-resolved second-harmonic-generation (SHG) microscopy. A polarization anisotropic image of the SHG light indicated that wrinkle direction in UVB-exposed skin is predominantly parallel to the orientation of dermal collagen fibers. Furthermore, collagen orientation in post-UVB-exposed skin with few wrinkles changed from that of UVB-exposed wrinkled skin to that of no-UVB-exposed skin. The method proposed has the potential to become a powerful non-invasive tool for assessment of cutaneous photoaging.