A high-voltage device includes a first frame-like isolation and a second frame-like isolation separated from each other, a first frame-like gate structure covering the first frame-like isolation, a second frame-like gate structure covering the second frame-like isolation, a first drain region enclosed by the first frame-like isolation, a second drain region enclosed by the second frame-like isolation, a first frame-like source region surrounding the first frame-like gate structure, a second frame-like source region surrounding the second frame-like gate structure, a first doped region surrounding the first and second frame-like gate structures, and a second doped region disposed between the first and second frame-like gate structures. The first and second drain regions, and the first and second frame-like source regions include a first conductivity type. The first and the second doped region include a second conductivity type. The first conductivity type and the second conductivity type are complementary to each other.