An optical unit includes: a lens holding frame configured to hold an objective optical system an image pickup device holding frame configured to hold an image pickup device including a light receiving section that detects an object image formed by the objective optical system, to which a first holding frame is interpolated and fitted a welding section provided on a fitting section of the lens holding frame and the image pickup device holding frame, configured to fix the lens holding frame and the image pickup device holding frame at a fitting position at which an image forming surface of the object image by the objective optical system and the light receiving section are made to coincide and a bonding material configured to fill a gap formed between the lens holding frame and the image pickup device holding frame.
