Use of ergothioneine is disclosed. Ergothioneine is used to manufacture drugs for activating Nrf2 signaling pathway of cell, in particular the damaged cell caused by ultraviolet radiation. Thus ergothioneine increases the expression of antioxidant molecules of damaged cells and promote Nrf2 nuclear translocation.本發明提供一種麥角硫因之用途,係應用於製備活化細胞之Nrf2訊息途徑之藥物,特別是經由紫外線照射後的損傷細胞,以提高損傷細胞的抗氧化分子之表現及促進Nrf2入核。