A keyboard device includes a substrate, keycaps, and a frame. The substrate has a top surface and a bottom surface and includes a welding-fixing portion. The welding-fixing portion includes a through hole and an arch-shaped bridge member. The arch-shaped bridge member is connected in the through hole and divides the through hole into partition holes. The arch-shaped bridge member has an arch portion and bridge bases. The arch portion protrudes from the top surface to form a recessed portion. The frame is disposed on the top surface and includes hollow holes respectively corresponding to the keycaps. The frame includes a welding member, and the welding member includes welding posts and a welding-fixing base. The welding posts respectively pass through spaces between the edge portion of the through hole and the arch-shaped bridge member. The welding-fixing base is received and fixed in the through hole and the recessed portion.