To provide a method of manufacturing a diffusion resistance with low noise and low variation in resistance.

There is provided a method of manufacturing a diffusion resistance element comprising: a step of forming a p-type diffusion layer 114 in the vicinity of a surface of a semiconductor substrate; a step of forming a cover film 125 which is an insulating film different from an interlayer insulating film and protects a surface of a first region of a p-type diffusion layer 114, which is to be a diffusion resistance body, on a surface of the first region; and a step of forming a p-type diffusion layer 116, which is to be a contact portion of the diffusion resistance body at a concentration higher than that of the first region in a second region contacting the first region of the cover film 125 after the step of forming the cover film 125.