An optical unit 1 includes: a lens holding frame 11 configured to hold an objective optical system 13 an image pickup device holding frame 12 configured to hold an image pickup device 21 including a light receiving section 21 a that detects an object image formed by the objective optical system 13, to which a first holding frame is interpolated and fitted a welding section 30 provided on a fitting section of the lens holding frame 11 and the image pickup device holding frame 12, configured to fix the lens holding frame 11 and the image pickup device holding frame 12 at a fitting position at which an image forming surface of the object image by the objective optical system 13 and the light receiving section 21a are made to coincide and a bonding material 31 configured to fill a gap formed between the lens holding frame 11 and the image pickup device holding frame 12.
