The history of methylmercury (MeHg) toxicity research goes back to Minamata disease. In Japan, histopathological examination of patients afflicted with Minamata disease, alongside meticulous investigations at both in vitro and in vivo, were robustly undertaken to elucidate the deleterious effects of MeHg. It is not an overstatement to assert that Japanese investigations on MeHg toxicity have spearheaded global advancements in this field. Nevertheless, more than half a century has passed since the onset of Minamata disease, yet the intricacies of MeHg toxicity remains enigmatic. Moreover, environmental pollution of mercury and toxic metals is a global problem that needs to be solved. Therefore, our research has focused on, "toxicology of MeHg" and "remediation of mercury and other toxic metals". This review discusses the molecular mechanisms underlying roles of autophagy in MeHg responses of mammalian cells, identification of an anti-MeHg natural product, analysis of bacterial mercury-resistant gene, and plant biotechnology using bacterial transporters for phytoremediation.