Scallops (Patinopecten yessoensis) are extensively cultured and landed in Japan. During the processing of scallops, large amounts of internal organs and shells are discharged as industrial wastes. To reduce the burden on the environment, effective utilization and disposal methods of the wastes are required. Therefore, we have screened for useful materials in scallop internal organs, and found ultraviolet (UV) absorbing compounds from scallop ovaries. Based on UV absorption, electrospray ionization-mass spectrometry (ESI-MS), ESI-MS/MS, and nuclear magnetic resonance (NMR) spectra, three UV absorbing compounds were identified as mycosporine-like amino acids (MAAs): shinorine, porphyra-334 (P-334), and mycosporine-glycine. To investigate whether MAAs can act as a UV protector for human cells, we examined the protective effects of the three MAAs on human fibroblast cells from UV irradiation. All of the three examined MAAs protected the cells from UV-induced cell death. In particular, mycosporine-glycine had the strongest effect. Further, we found a promotion effect of MAAs on the proliferation of human skin fibroblast cells. From these results, it was found that the three MAAs isolated from scallop ovaries have a protective effect on human cells against UV light. MAAs have potential applications in cosmetics and toiletries as a UV protectors and activators of cell proliferation.