The invention provides a dome cover, a camera device, an injection molding die, and an injection molding method in which generation of a weldline is suppressed and deterioration of an acquired image is suppressed. In one aspect of the invention, a dome cover is a dome cover that covers a camera. The dome cover includes a curved section having a curved shape and a skirt section having a cylinder shape and has a top section at the curved section and an opening end section at the skirt section. The thickness of the dome cover is largest at the top section and smallest at the opening end section, and continuously decreases from the top section toward the opening end section. The inner diameter and the outer diameter of the dome cover continuously increase from the top section toward the opening end section.