The present invention relates to methods of preventing or treating skin necroptosis diseases, including administering to subjects receptor-interacting protein kinase-3 (RIP3)-mixed lineage kinase domain-like protein (MLKL) pathway blockers or dabrafenib, and method of diagnosing of skin necroptosis diseases, including detecting phosphorylated MLKL. The RIP3-MLKL pathway blockers according to the present invention directly suppress RIP3 overexpressing in skin necroptosis diseases, or inhibit phosphorylation and translocation to plasma membranes of MLKL, subsequently induced therefrom, thereby effectively preventing skin cell death via necroptosis. Thus, the present invention can prevent or treat a variety of skin diseases caused by necroptosis.